Terminal apparatus, base station apparatus, and method

ABSTRACT

Provided is a terminal apparatus configured to release, based on receiving, via a DCCH from the base station apparatus, an RRC message including a part of session information of an MBS session, an MBS radio bearer used to receive the MBS session.

TECHNICAL FIELD

The present invention relates to a terminal apparatus, a base stationapparatus, and a method.

This application claims priority based on JP 2020-132233 filed on Aug.4, 2020, the contents of which are incorporated herein by reference.

BACKGROUND ART

In the 3rd Generation Partnership Project (3GPP) which is astandardization project for cellular mobile communication systems,technical study and standardization have been performed on the cellularmobile communication systems including radio access, core networks,services, and the like.

For example, in 3GPP, technical study and standardization have beenstarted on Evolved Universal Terrestrial Radio Access (E-UTRA) as aradio access technology (RAT) for cellular mobile communication systemsfor the 3.9th generation and the 4th generation. At present as well, in3GPP, technical study and standardization have been carried out onenhanced technology of E-UTRA. Note that E-UTRA may also be referred toas Long Term Evolution (LTE: registered trademark), and its enhancedtechnology may also be referred to as LTE-Advanced (LTE-A) andLTE-Advanced Pro (LTE-A Pro).

In 3GPP, technical study and standardization have been started on NewRadio or NR Radio access (NR) as a radio access technology (RAT) forcellular mobile communication systems for the 5th generation (5G). Atpresent as well, in 3GPP, technical study and standardization have beencarried out on enhanced technology of NR.

CITATION LIST Non Patent Literature

-   NPL 1: 3GPP RP-193248, “New Work Item on NR Multicast and Broadcast    Services”-   NPL 2: 3GPP TS 23.501 v16.5.0, “System Architecture for the 5G    System; Stage 2”-   NPL 3: 3GPP TS 36.300 v16.2.0, “Evolved Universal Terestrial Radio    Access (E-UTRA) and Evolved Universal Terestrial Radio Access    Network (E-UTRAN); Overall description; Stage 2”-   NPL 4: 3GPP TS 36.331 v16.1.0, “Evolved Universal Terestrial Radio    Access (E-UTRA); Radio Resource Control (RRC); Protocol    specifications”-   NPL 5: 3GPP TS 36.323 v16.1.0, “Evolved Universal Terestrial Radio    Access (E-UTRA); Packet Data Convergence Protocol (PDCP)    specification”-   NPL 6: 3GPP TS 36.322 v16.0.0, “Evolved Universal Terestrial Radio    Access (E-UTRA); Radio Link Control (RLC) protocol specification”-   NPL 7: 3GPP TS 36.321 v16.1.0, “Evolved Universal Terestrial Radio    Access (E-UTRA); Medium Access Control (MAC) protocol specification”-   NPL 8: 3GPP TS 37.340v 16.2.0, “Evolved Universal Terestrial Radio    Access (E-UTRA) and NR; Multi-Connectivity; Stage 2”-   NPL 9: 3GPP TS 38.300v 16.2.0, “NR; NR and NG-RAN Overall    description; Stage 2”-   NPL 10: 3GPP TS 38.331 v16.1.0, “NR; Radio Resource Control (RRC);    Protocol specifications”-   NPL 11: 3GPP TS 38.323 v16.1.0, “NR; Packet Data Convergence    Protocol (PDCP) specification”-   NPL 12: 3GPP TS 38.322 v16.1.0, “NR; Radio Link Control (RLC)    protocol specification”-   NPL 13: 3GPP TS 38.321 v16.1.0, “NR; Medium Access Control (MAC)    protocol specification”-   NPL 14: 3GPP TS 23.401 v16.7.0, “General Packet Radio Service (GPRS)    enhancements for Evolved Universal Terrestrial Radio Access Network    (E-UTRAN) access”-   NPL 15: 3GPP TS 26.346 v16.5.0, “Multimedia Broadcast/Multicast    Service (MBMS); Protocols and codecs”-   NPL 16: 3GPP TS 37.324 v16.1.0, “NR; Service Data Adaptation    Protocol (SDAP) specification”

SUMMARY OF INVENTION Technical Problem

As one aspect of the study of the enhanced technology of E-UTRA, inorder to provide multicast/broadcast services, Multimedia BroadcastMulticast Service (MBMS) transmission technology has been standardized.For the MBMS transmission, transmission using a Multicast BroadcastSingle Frequency Network (MBSFN) or a Single Cell Point-To-Multipoint(SC-PTM) is used.

In the transmission using the MBSFN, transmission of multicast/broadcastdata is performed using a Physical Multicast Channel (PMCH) for eachMulticast-Broadcast Single-Frequency Network (MBSFN) area includingmultiple cells. In contrast, in the transmission using the SC-PTM,transmission of multicast data is performed using a Physical DownlinkShared Channel (PDSCH) for each cell.

At the same time, multicast/broadcast services (Multicast BroadcastServices (MBS)) have been under study as the enhanced technology of NR.(NPL 1). In a case that the MBS is performed via NR, technology specificto NR which is different from that of E-UTRA, a core networkstandardized for 5G, and the like need to be taken into consideration.However, studies have not yet been carried out on detailed operationsfor efficiently receiving the MBS by using NR.

An aspect of the present invention is made in view of the circumstancesdescribed above, and has an object to provide a terminal apparatus, abase station apparatus, a method, and an integrated circuit that enableefficient reception of MBS by using NR.

Solution to Problem

In order to accomplish the object described above, an aspect of thepresent invention is contrived to provide the following means.Specifically, an aspect of the present invention is a terminal apparatusfor communicating with a base station apparatus, the terminal apparatusbeing configured to release, based on receiving, via a DCCH from thebase station apparatus, an RRC message including a part of sessioninformation of an MBS session, an MBS radio bearer used to receive theMBS session.

An aspect of the present invention is a terminal apparatus forcommunicating with a base station apparatus, the terminal apparatusbeing configured to release, based on receiving an MBS session on apoint-to-point basis, an MBS radio bearer used to receive the MBSsession.

An aspect of an embodiment of the present invention is a base stationapparatus for communicating with a terminal apparatus, the base stationapparatus being configured to cause the terminal apparatus to release,based on transmitting, via a DCCH to the terminal apparatus, an RRCmessage including a part of session information of an MBS session, anMBS radio bearer used to receive the MBS session.

An aspect of an embodiment of the present invention is a method for aterminal apparatus for communicating with a base station apparatus, themethod including releasing, based on receiving, via a DCCH from the basestation apparatus, an RRC message including a part of sessioninformation of an MBS session, an MBS radio bearer used to receive theMBS session.

An aspect of an embodiment of the present invention is a method for aterminal apparatus for communicating with a base station apparatus, themethod including releasing, based on receiving an MBS session on apoint-to-point basis, an MBS radio bearer used to receive the MBSsession.

An aspect of an embodiment of the present invention is a method for abase station apparatus for communicating with a terminal apparatus, themethod including causing the terminal apparatus to release, based ontransmitting, via a DCCH to the terminal apparatus, an RRC messageincluding a part of session information of an MBS session, an MBS radiobearer used to receive the MBS session.

Note that these comprehensive or specific aspects may be implemented ina system, an apparatus, a method, an integrated circuit, a computerprogram, or a recording medium, or may be implemented in any combinationof systems, apparatuses, methods, integrated circuits, computerprograms, and recording media.

Advantageous Effects of Invention

According to an aspect of the present invention, the terminal apparatuscan efficiently receive the MBS by using NR.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a communication system according toeach embodiment of the present invention.

FIG. 2 is a diagram of protocol stacks of a UP and a CP of a terminalapparatus and a base station apparatus in E-UTRA according to eachembodiment of the present invention.

FIG. 3 is a diagram of protocol stacks of the UP and the CP of theterminal apparatus and the base station apparatus in NR according toeach embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a flow of a procedure forvarious configurations in an RRC 208 and/or an RRC 308 according to eachembodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of the terminalapparatus according to each embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of the basestation apparatus according to each embodiment of the present invention.

FIG. 7 is an example of an ASN.1 notation included in a message relatedto reconfiguration of RRC connection in NR according to an embodiment ofthe present invention.

FIG. 8 is an example of an ASN.1 notation included in a message relatedto reconfiguration of RRC connection in E-UTRA according to anembodiment of the present invention.

FIG. 9 is a diagram illustrating a flow of a procedure for configurationof MBMS reception using an SC-PTM.

FIG. 10 is a diagram illustrating an example of ASN.1 notationrepresenting fields and/or information elements included in SystemInformation Block Type 20 (SIB20).

FIG. 11 is a diagram illustrating an example of ASN.1 notationrepresenting fields and/or information elements included in an SC-PTMconfiguration message (SCPTMConfiguration).

FIG. 12 is a diagram illustrating an example illustrating aconfiguration of an SDAP sublayer according to an embodiment of thepresent invention.

FIG. 13 is a diagram illustrating an example of a flow of a procedurefor configuration of MBS reception in NR according to an embodiment ofthe present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described indetail with reference to the drawings.

LTE (and LTE-A, LTE-A Pro) and NR may be defined as different RadioAccess Technologies (RATs). The NR may be defined as a technologyincluded in the LTE. The LTE may be defined as a technology included inthe NR. The LTE connectable to the NR by using Multi Radio Dualconnectivity may be distinguished from the existing LTE. The LTE inwhich a 5GC is used as a core network may be distinguished from aconventional LTE, where an EPC is used as a core network. The presentembodiment may be applied to the NR, the LTE and other RATs. Termsassociated with the LTE and the NR are used in the followingdescription. However, the present embodiment may be applied to othertechnologies using other terms. In the present embodiment, the term“E-UTRA” may be replaced with “LTE,” and the term “LTE” may be replacedwith “E-UTRA.”

FIG. 1 is a schematic diagram of a communication system according toeach embodiment of the present invention.

An E-UTRA 100 is a radio access technology described in NPL 3 or thelike, and includes a cell group (CG) including one or multiple frequencybands. An E-UTRAN Node B (eNB) 102 is a base station apparatus of theE-UTRA 100. An Evolved Packet Core (EPC) 104 is a core network describedin NPL 14 and the like and is designed as a core network for the E-UTRA100. An interface 112 is an interface between the eNB 102 and the EPC104, where there is a control plane (CP) through which control signalsare transferred and a user plane (UP) through which user data istransferred.

An NR 106 is a radio access technology described in NPL 9 and the like,and includes a cell group (CG) including one or multiple frequencybands. A gNodeB (gNB) 108 is a base station apparatus in the NR 106. A5GC 110 is a core network described in NPL 2 and the like, and isdesigned as a core network for the NR 106, but may also be used as acore network for the E-UTRA 100 and including a function to connect tothe 5GC 110. Hereinafter, the E-UTRA 100 may include the E-UTRA 100including a function to connect to the 5GC 110.

An interface 114 is an interface between the eNB 102 and the 5GC 110, aninterface 116 is an interface between the gNB 108 and the 5GC 110, aninterface 118 is an interface between the gNB 108 and the EPC 104, aninterface 120 is an interface between the eNB 102 and the gNB 108, andan interface 124 is an interface between the EPC 104 and 5GC 110. Theinterface 114, the interface 116, the interface 118, the interface 120,the interface 124, and the like may be interfaces that allow a CP only,an UP only, or both the CP and UP to pass through. The interface 114,the interface 116, the interface 118, the interface 120, the interface124, and the like may be absent depending on a communication systemprovided by a network operator.

A UE 122 is a terminal apparatus supporting one or all of the E-UTRA 100and the NR 106. As described in one or all of NPL 3 and NPL 9, in a casethat the UE 122 connects to a core network via one or all of the E-UTRA100 and the NR 106, a logical path called a radio bearer (RB) isestablished between the UE 122 and one or all of the E-UTRA 100 and theNR 106. The radio bearer used for the CP is referred to as a SignalingRadio Bearer (Signaling Radio Bearer (SRB)), and the radio bearer usedfor the UP is referred to as a Data Radio Bearer (DRB). Each RB isassigned an RB identity (or an RB ID) and uniquely identified. The RBidentity for the SRB is referred to as an SRB identity (or an SRB ID),and the RB identity for the DRB is referred to as a DRB identity (or aDRB ID).

As described in NPL 3, in a case that a connection destination corenetwork for the UE 122 is an EPC 104, each DRB established between theUE 122 and any or all of the E-UTRA 100 and the NR 106 is uniquelylinked to each Evolved Packet System (EPS) bearer passing through theEPC 104. Each EPS bearer is assigned an EPS bearer identity (or ID), anduniquely identified. Identical QoS is ensured for data passing throughan identical EPS bearer.

As described in NPL 9, in a case that a connection destination corenetwork of the UE 122 is the 5GC 110, one or multiple DRBs establishedbetween the UE 122 and one or all of the E-UTRA 100 and the NR 106 arefurther linked to one of the Packet Data Unit (PDU) sessions establishedin the 5GC 110. One or multiple QoS flows are present in each PDUsession. Each DRB may be mapped to one or multiple QoS flows present inthe linked PDU session or to none of the QoS flows. Each PDU session isidentified by a PDU session identity (or ID). Each QoS flow isidentified by a QoS flow identity. Identical QoS is ensured for datapassing through an identical QoS flow.

In the EPC 104, either of the PDU sessions or the QoS flows is absent ornone of the PDU sessions and the QoS flows are present. No EPS bearersare present in the 5GC 110. In a case that the UE 122 is connected tothe EPC 104, the UE 122 has information of the EPS bearers, but does nothave any or all of the PDU sessions and the QoS flows. In a case thatthe UE 122 is connected to the 5GC 110, the UE 122 has information ofany or all of the PDU sessions and the QoS flows, but does not haveinformation of the EPS bearers.

Note that, in the following description, the eNB 102 and/or the gNB 108is simply referred to as a base station apparatus, and the UE 122 isalso simply referred to as a terminal apparatus.

FIG. 2 is a diagram of protocol stacks of UP and CP of a terminalapparatus and a base station apparatus in an E-UTRA radio access layeraccording to each embodiment of the present invention.

FIG. 2(A) is a diagram of a protocol stack of the UP used in a case thatthe UE 122 communicates with the eNB 102 in the E-UTRA 100.

A Physical layer (PHY) 200 is a radio physical layer and provides atransmission service to a higher layer by using a physical channel. ThePHY 200 is connected with a Medium Access Control layer (MAC) 202 of ahigher layer to be described below via transport channels. Data isexchanged between the MAC 202 and the PHY 200 via the transportchannels. The data is transmitted and/or received via radio physicalchannels between the PHYs of the UE 122 and the eNB 102. In the PHY 200,in order to identify various pieces of control information, a RadioNetwork Temporary Identifire (RNTI) is used.

The MAC 202 is a medium access control layer that maps various logicalchannels to various transport channels. The MAC 202 is connected with aradio link control layer (RLC) 204 of a higher layer to be describedbelow via logical channels. The major classifications of the logicalchannel depend on the type of information to be transmitted,specifically, the logical channels are classified into control channelsfor transmitting control information and traffic channels fortransmitting user information. The MAC 202 has a function of controllingthe PHY 200 in order to perform discontinuous reception (DRX) and/ordiscontinuous transmission (DTX), a function of performing a randomaccess procedure, a function of notifying transmit power information, afunction of performing HARQ control, and the like (NPL 7).

Uplink (UL) and/or downlink (DL) logical channels used in E-UTRA will bedescribed.

A Broadcast Control Channel (BCCH) may be a downlink logical channel forbroadcasting control information, such as system information (SI).

A Paging Control Channel (PCCH) may be a downlink logical channel forcarrying a paging message. The PCCH may be used for notifying change ofthe system information.

A Common Control Channel (CCCH) may be a logical channel fortransmitting control information between the UE 122 and the eNB 102. TheCCCH may be used in a case that the UE 122 does not have Radio ResourceControl (RRC) connection to be described later. The CCCH may be usedbetween the base station apparatus and multiple terminal apparatuses.

A Dedicated Control Channel (DCCH) may be a logical channel fortransmitting dedicated control information in a point-to-pointbi-directional manner between the UE 122 and the eNB 102. The dedicatedcontrol information may be control information dedicated to eachterminal apparatus. The DCCH may be used in a case that the UE 122 andthe eNB 102 have Radio Resource Control (RRC) connection to be describedlater therebetween.

A Dedicated Traffic Channel (DTCH) may be a logical channel fortransmitting user data in a point-to-point manner between the UE 122 andthe eNB 102. The DTCH may be a logical channel for transmittingdedicated user data. The dedicated user data may be user data dedicatedto each terminal apparatus. The DTCH may be present in both the uplinkand the downlink.

A Multicast Traffic Channel (MTCH) may be a point-to-multipoint downlinkchannel for transmitting data from the eNB 102 to the UE 122. The MTCHmay be a multicast logical value channel. The MTCH may be used by the UE122 only in a case that the UE 122 receives MBMS.

A Multicast Control Channel (MCCH) may be a point-to-multipoint downlinkchannel for transmitting MBMS control information for one or multipleMTCHs from the eNB 102 to the UE 122. The MCCH may be a multicastlogical value channel. The MCCH may be used by the UE 122 only in a casethat the UE 122 receives MBMS, or in a case that the UE 122 isinterested in receiving MBMS.

A Single Cell Multicast Traffic Channel (SC-MTCH) may be apoint-to-multipoint downlink channel for transmitting data from the eNB102 to the UE 122 by using the SC-PTM. The SC-MTCH may be a multicastlogical channel. The SC-MTCH may be used by the UE 122 only in a casethat the UE 122 receives MBMS by using the Single CellPoint-To-Multipoint (SC-PTM).

A Single Cell Multicast Control Channel (SC-MCCH) may be apoint-to-multipoint downlink channel for transmitting MBMS controlinformation for one or multiple SC-MTCHs from the eNB 102 to the UE 122.The SC-MCCH may be a multicast logical channel. The SC-MCCH may be usedby the UE 122 only in a case that the UE 122 receives MBMS by using theSC-PTM or a case that the UE 122 is interested in receiving MBMS byusing the SC-PTM.

Mapping between the uplink logical channels and the transport channelsin E-UTRA will be described.

The CCCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

The DCCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

The DTCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

Mapping between the downlink logical channels and the transport channelsin E-UTRA will be described.

The BCCH may be mapped to a Broadcast Channel (BCH) and/or a DownlinkShared Channel (DL-SCH) being a downlink transport channel.

The PCCH may be mapped to a Paging Channel (PCH) being a downlinktransport channel.

The CCCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The DCCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The DTCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The MTCH may be mapped to a Multicast Channel (MCH) being a downlinktransport channel.

The MCCH may be mapped to a Multicast Channel (MCH) being a downlinktransport channel.

The SC-MTCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel

The SC-MTCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The RLC 204 is a radio link control layer that performs segmentation ofdata received from a Packet Data Convergence Protocol Layer (PDCP) 206of a higher layer to be described below, and adjusts the data size suchthat a lower layer can properly transmit the data. The RLC 204 has threemodes, namely a Transparent Mode (TM), an Unacknowledged Mode (UM), andan Acknowledged Mode (AM). In the TM, segmentation of data received froma higher layer is not performed, and addition of an RLC header is notperformed. In the UM, segmentation of data received from a higher layer,addition of an RLC header, and the like are performed, butretransmission control of data is not performed. In the AM, segmentationof data received from a higher layer, addition of an RLC header,retransmission control of data, and the like are performed. Aretransmission control function may be a function for ensuring Qualityof Service (QoS) required by each piece of data. In a case thatretransmission control of data is performed, information of undelivereddata transmitted from a reception side to a transmission side of the RLCis referred to as a status report. An indication to prompt the statusreport transmitted from the transmission side to the reception side ofthe RLC is referred to as a poll. Note that data transmitted to a lowerlayer in the TM may be referred to as a TMD PDU, data transmitted to alower layer in the UM may be referred to as a UMD PDU, and datatransmitted to a lower layer in the AM may be referred to as an AMD PDU.(NPL 6).

The PDCP 206 is a packet data convergence protocol layer for efficientlytransmitting user data such as an IP packet in radio sections. The PDCP206 may have a header compression or decompression function. The PDCP206 may have a data ciphering or deciphering function. The PDCP 206 mayhave a data integrity protection or integrity validation function. ThePDCP 206 may have a re-ordering function (NPL 5).

Note that data processed in the MAC 202, the RLC 204, and the PDCP 206are referred to as a MAC Protocol Data Unit (PDU), an RLC PDU, and aPDCP PDU, respectively. Data delivered from or to a higher layer to orfrom the MAC 202, the RLC 204, and the PDCP 206 is referred to as a MACService Data Unit (SDU), an RLC SDU, and a PDCP SDU, respectively. Asegmented RLC SDU is referred to as an RLC SDU segment.

In order to make a distinction between data use and control use, thePDCP PDU may be referred to as a PDCP DATA PDU (PDCP Data PDU, PDCP dataPDU) and a PDCP CONTROL PDU (PDCP Control PDU, PDCP control PDU). Inorder to make a distinction between data use and control use, the RLCPDU may be referred to as an RLC DATA PDU (RLC Data PDU, RLC data PDU)and an RLC CONTROL PDU (RLC Control PDU, RLC control PDU, RLC controlODU).

FIG. 2(B) is a protocol stack diagram of the CP used by the UE 122 incommunicating with the eNB 102 and a Mobility Management Entity (MME)used as a logical node providing functions such as authentication andmobility management in the E-UTRA 100.

In the protocol stack of the CP, a Radio Resource Control layer (RRC)208 and a non Access Strarum (NAS) 210 are present in addition to thePHY 200, the MAC 202, the RLC 204, and the PDCP 206. The RRC 208 is aradio link control layer that performs processing such as establishment,re-establishment, suspension, resumption, and the like of an RRCconnection, reconfiguration of the RRC connection, for example,configuration of the radio bearer (RB) and the cell group such asestablishment, change, or release, control of logical channels,transport channels, and physical channels, and the like, and furtherperforms configuration of handover and measurement, and the like. TheRBs may be classified into a Signaling Radio Bearer (Signaling RadioBearer (SRB)) and a Data Radio Bearer (DRB), and the SRB may be used asa path for transmitting an RRC message which is control information. TheDRB may be used as a path for transmitting the user data. Each RB may beconfigured between the RRCs 208 of the eNB 102 and the UE 122. A portionof the RB including the RLC 204 and the logical channel may be referredto as an RLC bearer (NPL 4). In contrast to a NAS layer for carryingsignals between the MME and the UE 122, a part of layers or all oflayers of the PHY 200, the MAC 202, the RLC 204, the PDCP 206, and theRRC 208 for carrying signals and data between the UE 122 and the eNB 102may be referred to as an Access Strarum (AS) layer.

For the SRB, the following SRB0 to SRB2 may be defined, or other SRBsmay be defined. SRBO may be an SRB used for an RRC message and using aCommon Control CHannel (CCCH) corresponding to a logical channel. SRB1may be an SRB for the RRC message (which may include a piggybacked NASmessage) and for the NAS message prior to the establishment of SRB2, andthe Dedicated Control CHannel (DCCH) corresponding to a logical channelmay be used for all cases. SRB2 may be an SRB for the NAS message, andthe DCCH corresponding to a logical channel may be used for all cases.SRB2 may have a lower priority than SRB1.

The RRC message may be transmitted using the BCCH of the logicalchannel, may be transmitted using the PCCH of the logical channel, maybe transmitted using the MCCH of the logical channel, may be transmittedusing the CCCH of the logical channel, or may be transmitted using theDCCH of the logical channel.

For example, the RRC message transmitted using the BCCH may include aMaster Information Block described in NPL 4, may include a SystemInformation Block of each type, or may include another RRC message.

For example, the RRC message transmitted using the PCCH may include apaging message described in NPL 4, or may include another RRC message.

For example, the RRC message transmitted using the MCCH may include aMulticast Broadcast Single Frequency Network (MBSFN) area configuration(MBSFNAreaConfiguration) described in NPL 4, may include an MBMScontinuing request (MBMSContinuingRequest), or may include another RRCmessage

For example, the RRC message transmitted in an uplink (UL) directionusing the CCCH may include an RRC connection request message (RRCConnection Request), an RRC connection resume request message (RRCConnection Resume Request), an RRC connection reestablishment requestmessage (RRC Connection Reestablishment Request), or the like describedin NPL 4, or may include another RRC message. For example, the RRCmessage transmitted in a downlink (DL) direction using the CCCH mayinclude an RRC connection reject message (RRC Connection Reject), an RRCconnection setup message (RRC Connection Setup), an RRC connectionreestablishment message (RRC Connection Reestablishment), an RRCconnection reestablishment reject message (RRC ConnectionReestablishment Reject), or the like described in NPL 4, or may includeanother RRC message.

For example, the RRC message transmitted in the uplink (UL) directionusing the DCCH may include a measurement report message (MeasurementReport), an RRC connection reconfiguration complete message (RRCConnection Reconfiguration Complete), an RRC connection setup completemessage (RRC Connection Setup Complete), an RRC connectionreestablishment complete message (RRC Connection ReestablishmentComplete), or the like described in NPL 4, or may include another RRCmessage. For example, the RRC message transmitted in the downlink (DL)direction using the CCCH may include an RRC connection reconfigurationmessage (RRC Connection Reconfiguration), an RRC connection releasemessage (RRC Connection Release), or the like described in NPL 4, or mayinclude another RRC message.

The functional classification of the MAC 202, the RLC 204, the PDCP 206,and the RRC 208 described above is an example, and some or all of therespective functions may not be implemented. Some or all of thefunctions of each layer may be included in another layer.

Note that an IP layer and a Transmission Control Protocol (TCP) layer, aUser Datagram Protocol (UDP) layer, an application layer, and the like,which are higher layers than the IP layer, are higher layers than a PDCPlayer (not illustrated). An RRC layer and a non Access Strarum (NAS)layer are also higher layers than the PDCP layer (not illustrated). Inother words, the PDCP layer is a lower layer than the RRC layer, the NASlayer, the IP layer, and the Transmission Control Protocol (TCP) layer,the User Datagram Protocol (UDP) layer, and the application layer, whichare higher layers than the IP layer.

FIG. 3 is a diagram of protocol stacks of UP and CP of a terminalapparatus and a base station apparatus in an NR radio access layeraccording to each embodiment of the present invention.

FIG. 3(A) is a diagram of the protocol stack of the UP used by the UE122 in communicating with the gNB 108 in the NR 106.

A physical layer (PHY) 300 is a radio physical layer of the NR and mayprovide a transmission service to a higher layer by using a physicalchannel. The PHY 300 may be connected with the Medium Access Controllayer (MAC) 302 of a higher layer to be described below via thetransport channels. Data may be exchanged between the MAC 302 and thePHY 300 via the transport channels. The data may be transmitted and/orreceived between the PHYs of the UE 122 and the gNB 108 via the radiophysical channel. In the PHY 200, in order to identify various pieces ofcontrol information, a Radio Network Temporary Identifire (RNTI) may beused.

Now, the physical channels will be described.

The following physical channels may be used for the radio communicationbetween the terminal apparatus and the base station apparatus.

-   Physical Broadcast CHannel (PBCH)-   Physical Downlink Control CHannel (PDCCH)-   Physical Downlink Shared CHannel (PDSCH)-   Physical Uplink Control CHannel (PUCCH)-   Physical Uplink Shared CHannel (PUSCH)-   Physical Random Access CHannel (PRACH)

The PBCH is used to broadcast system information required by theterminal apparatuses.

The PBCH may be used to broadcast time indexes (SSB-Indexes) within theperiodicity of synchronization signal blocks (also referred to asSS/PBCH blocks) in NR.

The PDCCH is used to transmit (or carry) downlink control information(DCI) in a case of downlink radio communication (radio communicationfrom the base station apparatus 3 to the terminal apparatus). Here, oneor multiple pieces of DCI (which may also be referred to as DCI formats)are defined for transmission of the downlink control information. Inother words, a field for the downlink control information is defined asDCI and is mapped to information bits. The PDCCH is transmitted in aPDCCH candidate. The terminal apparatus monitors a set of PDCCHcandidates in the serving cell. The monitoring means an attempt todecode the PDCCH in accordance with a certain DCI format. The certainDCI format may be used for scheduling of the PUSCH in the serving cell.The PUSCH may be used for transmission of user data, transmission of RRCmessages, and the like.

The PUCCH is used to transmit Uplink Control Information (UCI) in a caseof uplink radio communication (radio communication from the terminalapparatus to the base station apparatus). Here, the uplink controlinformation may include Channel State Information (CSI) used to indicatea downlink channel state. The uplink control information may includeScheduling Request (SR) used to request an UL-SCH resource. The uplinkcontrol information may include a Hybrid Automatic Repeat requestACKnowledgement (HARQ-ACK).

The PDSCH may be used to transmit downlink data (Downlink Shared CHannel(DL-SCH)) from the MAC layer. In a case of the downlink, the PDSCH isalso used to transmit System Information (SI), a Random Access Response(RAR), and the like.

The PUSCH may be used to transmit uplink data (Uplink-Shared CHannel(UL-SCH)) from the MAC layer or to transmit the HARQ-ACK and/or CSIalong with the uplink data. The PUSCH may be used to transmit CSI onlyor a HARQ-ACK and CSI only. In other words, the PUSCH may be used totransmit the UCI only. The PDSCH or the PUSCH may be used to transmitRRC signalling (also referred to as RRC messages) and MAC controlelements. In this regard, in the PDSCH, the RRC signalling transmittedfrom the base station apparatus may be signalling common to multipleterminal apparatuses in a cell The RRC signalling transmitted from thebase station apparatus may be dedicated signalling for a certainterminal apparatus (also referred to as dedicated signalling). In otherwords, terminal apparatus-specific (UE-specific) information may betransmitted through dedicated signalling to the certain terminalapparatus. The PUSCH may be used to transmit UE capabilities in theuplink.

The PRACH may be used for transmitting a random access preamble. ThePRACH may be used for indicating the initial connection establishmentprocedure, the handover procedure, the connection re-establishmentprocedure, synchronization (timing adjustment) for uplink transmission,and a request for a PUSCH (UL-SCH) resource.

The MAC 302 is a medium access control layer that maps various logicalchannels to various transport channels. The MAC 302 may be connectedwith the Radio Link Control layer (RLC) 304 of a higher layer to bedescribed below via the logical channels. The classification of thelogical channel depends on the type of information to be transmitted,and the logical channels may be classified into the control channels fortransmitting the control information and the traffic channels fortransmitting the user information. The MAC 302 may have a function ofcontrolling the PHY 300 in order to perform the Discontinuous Receptionand Transmission (DRX and DTX), a function of performing the randomaccess procedure, a function of notifying the transmit powerinformation, a function of performing the HARQ control, and the like(NPL 13).

Uplink (UL) and/or downlink (DL) logical channels used in NR will bedescribed.

A Broadcast Control Channel (BCCH) may be a downlink logical channel forbroadcasting control information, such as system information (SI).

A Paging Control Channel (PCCH) may be a downlink logical channel forcarrying a paging message.

A Common Control Channel (CCCH) may be a logical channel fortransmitting control information between the UE 122 and the gNB 108. TheCCCH may be used in a case that the UE 122 does not have RRC connection.The CCCH may be used between the base station apparatus and multipleterminal apparatuses.

A Dedicated Control Channel (DCCH) may be a logical channel fortransmitting dedicated control information in a point-to-pointbi-directional manner between the UE 122 and the gNB 108. The dedicatedcontrol information may be control information dedicated to eachterminal apparatus. The DCCH may be used in a case that the UE 122 hasRRC connection.

A Dedicated Traffic Channel (DTCH) may be a logical channel fortransmitting user data in a point-to-point manner between the UE 122 andthe gNB 108. The DTCH may be a logical channel for transmittingdedicated user data. The dedicated user data may be user data dedicatedto each terminal apparatus. The DTCH may be present in both the uplinkand the downlink.

Mapping between the uplink logical channels and the transport channelsin NR will be described.

The CCCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

The DCCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

The DTCH may be mapped to an Uplink Shared Channel (UL-SCH) being anuplink transport channel.

Mapping between the downlink logical channels and the transport channelsin NR will be described.

The BCCH may be mapped to a Broadcast Channel (BCH) and/or a DownlinkShared Channel (DL-SCH) being a downlink transport channel.

The PCCH may be mapped to a Paging Channel (PCH) being a downlinktransport channel.

The CCCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The DCCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The DTCH may be mapped to a Downlink Shared Channel (DL-SCH) being adownlink transport channel.

The RLC 304 is a radio link control layer that performs segmentation ofdata received from a Packet Data Convergence Protocol Layer (PDCP) 306of a higher layer to be described below, and adjusts the data size suchthat a lower layer can properly transmit the data. The RLC 304 has threemodes, namely a Transparent Mode (TM), an Unacknowledged Mode (UM), andan Acknowledged Mode (AM). In the TM, segmentation of data received froma higher layer is not performed, and addition of an RLC header is notperformed. In the UM, segmentation of data received from a higher layer,addition of an RLC header, and the like are performed, butretransmission control of data is not performed. In the AM, segmentationof data received from a higher layer, addition of an RLC header,retransmission control of data, and the like are performed. Aretransmission control function may be a function for ensuring Qualityof Service (QoS) required by each piece of data. In a case thatretransmission control of data is performed, information of undelivereddata transmitted from a reception side to a transmission side of the RLCis referred to as a status report. An indication to prompt the statusreport transmitted from the transmission side to the reception side ofthe RLC is referred to as a poll. Note that data transmitted to a lowerlayer in the TM may be referred to as a TMD PDU, data transmitted to alower layer in the UM may be referred to as a UMD PDU, and datatransmitted to a lower layer in the AM may be referred to as an AMD PDU.(NPL 12).

The PDCP 306 is a packet data convergence protocol layer for efficientlytransmitting user data such as an IP packets in radio sections. The PDCP306 may have a header compression or decompression function. The PDCP306 may have a data ciphering or deciphering function, and a dataintegrity protection or integrity validation function. The PDCP 306 mayinclude a reordering function (NPL 11).

A Service Data Adaptation Protocol (SDAP) 310 is a service dataadaptation protocol layer that has functions to map the DRB to adownlink QoS flow transmitted from the 5GC 110 to the terminal apparatusvia the base station apparatus, to map the DRB to an uplink QoS flowtransmitted from the terminal apparatus to the 5GC 110 via the basestation apparatus, and to store mapping rule information (NPL 16).

Note that the data processed in the MAC 302, the RLC 304, the PDCP 306,and the SDAP 310 are referred to as a MAC Protocol Data Unit (PDU), anRLC PDU, a PDCP PDU, and an SDAP PDU, respectively. Data delivered fromor to a higher layer to or from the MAC 302, the RLC 304, the PDCP 306,and the SDAP 310 is referred to as a MAC Service Data Unit (SDU), an RLCSDU, a PDCP SDU, and an SDAP SDU, respectively. A segmented RLC SDU isreferred to as an RLC SDU segment.

In order to make a distinction between data use and control use, theSDAP PDU may be referred to as an SDAP DATA PDU (SDAP Data PDU, SDAPdata PDU) and an SDAP CONTROL PDU (SDAP Control PDU, SDAP control PDU),respectively. In order to make a distinction between data use andcontrol use, the PDCP PDU may be referred to as a PDCP DATA PDU (PDCPData PDU, PDCP data PDU) and a PDCP CONTROL PDU (PDCP Control PDU, PDCPcontrol PDU). In order to make a distinction between data use andcontrol use, the RLC PDU may be referred to as an RLC DATA PDU (RLC DataPDU, RLC data PDU) and an RLC CONTROL PDU (RLC Control PDU, RLC control)PDU), respectively.

FIG. 3(B) is a protocol stack diagram of the CP used by the UE 122 incommunicating with the gNB 108 and an Access and Mobility Managementfunction (AMF) used as a logical node providing functions such asauthentication and mobility management in the NR 106.

In the protocol stack of the CP, a Radio Resource Control layer (RRC)308 and a non Access Strarum (NAS) 312 are present in addition to thePHY 300, the MAC 302, the RLC 304, and the PDCP 306. The RRC 308 is aradio link control layer that performs processing such as establishment,re-establishment, suspension, resumption, and the like of an RRCconnection, reconfiguration of the RRC connection, for example,configuration of the radio bearer (RB) and the cell group such asestablishment, change, or release, control of logical channels,transport channels, and physical channels, and the like, and furtherperforms configuration of handover and measurement, and the like. TheRBs may be classified into a Signaling Radio Bearer (Signaling RadioBearer (SRB)) and a Data Radio Bearer (DRB), and the SRB may be used asa path for transmitting an RRC message which is control information. TheDRB may be used as a path for transmitting the user data. Each RB may beconfigured between RRCs 308 of the gNB 108 and the UE 122. A portion ofthe RB including the RLC 304 and the logical channel may be referred toas an RLC bearer (NPL 10). In contrast to the NAS layer carrying signalsbetween the AMF and the UE 122, some or all of the layers of the PHY300, the MAC 302, the RLC 304, the PDCP 306, the RRC 308, and the SDAP310 carrying signals and data between the UE 122 and the gNB 108 may bereferred to as Access Strarum (AS) layers.

For the SRB, the following SRB0 to SRB3 may be defined, or other SRBsmay be defined. SRB0 may be an SRB used for an RRC message and using aCommon Control CHannel (CCCH) corresponding to a logical channel. SRB1may be an SRB for the RRC message (which may include a piggybacked NASmessage) and for the NAS message prior to the establishment of SRB2, andthe Dedicated Control CHannel (DCCH) corresponding to a logical channelmay be used for all cases. SRB2 may be an SRB for the NAS message, andthe DCCH corresponding to a logical channel may be used for all cases.SRB2 may have a lower priority than SRB 1. SRB3 may be an SRB for aparticular RRC message in a case that the UE 122 is configured withEN-DC, NGEN-DC, or NR-DC to be described later or the like, and the DCCHcorresponding to a logical channel may be used for all cases. Other SRBsmay also be provided for other applications.

The RRC message may be transmitted using the BCCH of the logicalchannel, may be transmitted using the PCCH of the logical channel, maybe transmitted using the CCCH of the logical channel, or may betransmitted using the DCCH of the logical channel.

For example, the RRC message transmitted using the BCCH may include aMaster Information Block (MIB) described in NPL 10, may include a SystemInformation Block (SIB) of each type, or may include another RRCmessage. For example, the RRC message transmitted using the PCCH mayinclude a paging message described in NPL 10, or may include another RRCmessage.

For example, the RRC message transmitted in the uplink (UL) directionusing the CCCH may include an RRC setup request message (RRC SetupRequest), an RRC resume request message (RRC Resume Request), an RRCreestablishment request message (RRC Reestablishment Request), an RRCsystem information request message (RRC System Info Request), or thelike described in NPL 10, or may include another RRC message. Forexample, the RRC message transmitted in the downlink (DL) directionusing the CCCH may include an RRC connection reject message (RRCReject), an RRC setup message (RRC Setup), or the like described in NPL10, or may include another RRC message.

For example, the RRC message transmitted in the uplink (UL) directionusing the DCCH may include a measurement report message (MeasurementReport), an RRC reconfiguration complete message (RRC ReconfigurationComplete), an RRC setup complete message (RRC Setup Complete), an RRCreestablishment complete message (RRC Reestablishment Complete), tan RRCresume complete message (RRC Resume Complete), or the like described inNPL 10, or may include another RRC message. For example, the RRC messagetransmitted in the downlink (DL) direction using the CCCH may include anRRC reconfiguration message (RRC Reconfiguration), an RRC resume message(RRC Resume), an RRC release message (RRC Release), an RRCreestablishment message (RRC Reestablishment), or the like described inNPL 10, or may include another RRC message.

The functional classification of the MAC 302, the RLC 304, the PDCP 306,the SDAP 310, and the RRC 308 described above is an example, and some orall of the functions may not be implemented. Some or all of thefunctions of each layer may be included in another layer.

Note that a higher layer (not illustrated) than the AS layer may bereferred to as a PDU layer, as described in NPL 2. The PDU layer mayinclude any or all of an IP layer, a Transmission Control Protocol (TCP)layer and a User Datagram Protocol (UDP) layer that are higher layersthan the IP layer, or other layers. The application layer may be ahigher layer than the PDU layer or may be included in the PDU layer.Note that the PDU layer may be a higher layer with respect to the userplane of the AS layer. The RRC layer and the non Access Strarum (NAS)layer may also be a higher layer than one or all of the SDAP layer andthe PDCP layer (this is not illustrated). In other words, one or all ofthe SDAP layer and the PDCP layer are lower layers than any or all ofthe RRC layer, the NAS layer, the IP layer, and the Transmission ControlProtocol (TCP) layer, the User Datagram Protocol (UDP) layer, and theapplication layer that are higher layers than the IP layer.

Note that, in each embodiment of the present invention, any or all ofthe following may belong to the application layer: a Session InitiationProtocol (SIP), a Session Description Protocol (SDP), and the like usedfor an IP Multimedia Subsystem (IMS) being one service networkstandardized in 3GPP; a Real-time Transport Protocol (RTP), a Real-timeTransport Control Protocol (RTCP), a HyperText Transfer Protocol (HTTP),and the like used for media communication or media communicationcontrol; and codecs of various media and the like.

Note that the RRC layer of the terminal apparatus may perform any or allof establishment, configuration, and control on the physical layer, theMAC layer, the RLC layer, the PDCP layer, and the SDAP layer of theterminal apparatus. The RRC layer of the terminal apparatus mayestablish and/or configure the physical layer, the MAC layer, the RLClayer, the PDCP layer, and the SDAP layer in accordance with the RRCmessage transmitted from the RRC layer of the base station apparatus.The MAC layer, the RLC layer, the PDCP layer, and the SDAP layer mayrespectively be referred to as a MAC sublayer, an RLC sublayer, a PDCPsublayer, and an SDAP sublayer.

Note that an entity may refer to each of the layers belonging to the ASlayer configured for one or all of the terminal apparatus and the basestation apparatus or the function of each layer. Specifically, thephysical layer (PHY layer), the MAC layer, the RLC layer, the PDCPlayer, the SDAP layer, and the RRC layer, on which any or all ofestablishment, configuration, and control is performed for one or all ofthe terminal apparatus and the base station apparatus, or the functionsof the respective layers may be referred to as a physical entity (PHYentity), a MAC entity, an RLC entity, a PDCP entity, an SDAP entity, andan RRC entity, respectively. One or multiple entities may be included ineach layer. Any or all of establishment, configuration, and control maybe performed on the PDCP entity and the RLC entity for each radiobearer. Any or all of establishment, configuration, and control may beperformed on the MAC entity for each cell group. Any or all ofestablishment, configuration, and control may be performed on the SDAPentity for each PDU session.

Note that a COUNT value may be used in a case that processing forciphering or integrity protection is performed in the PDCP layer or thePDCP entity. The COUNT value may include a Hyper Frame Number (HFN) anda Sequence Number (SN) added to the header of the PDCP PDU. The sequencenumber may be incremented by one each time a PDCP DATA PDU is generatedby the PDCP layer or PDCP entity on the transmission side. The HFN maybe incremented by one each time the sequence number reaches the maximumvalue. In order to manage the COUNT value on the transmission side andthe reception side, a part or all of the following state variables of(A) to (F) may be used:

-   (A) A state variable indicating the COUNT value of the PDCP SDU to    be subsequently transmitted. The state variable may be a state    variable referred to as TX_NEXT described in NPL 11;-   (B) A state variable indicating the sequence number of the PDCP SDU    to be subsequently transmitted, in the present PDCP entity. The    state variable may be a state variable referred to as    Next_PDCP_TX_SN described in NPL 5;-   (C) A state variable indicating the HFN value used for generating    the COUNT value of the PDCP PDU in the present PDCP entity. The    state variable may be a state variable referred to as TX_HFN    described in NPL 5;-   (D) A state variable indicating the COUNT value of the PDCP SDU    expected to be subsequently received on the reception side of the    PDCP entity. The state variable may be a state variable referred to    as RX_NEXT described in NPL 11;-   (E) A state variable indicating the sequence number of the PDCP SDU    expected to be subsequently received on the reception side of the    present PDCP entity. The state variable may be a state variable    referred to as Next_PDCP_RX_SN described in NPL 5;-   (F) A state variable indicating the HFN value used for generating    the COUNT value for a received PDCP PDU in the present PDCP entity.    The state variable may be a state variable referred to as RX_ HFN    described in NPL 5.

In the PDCP layer or the PDCP entity, re-ordering may be processing forstoring the PDCP SDUs in a receive buffer and delivering the PDCP SDUsto a higher layer according to the order of the COUNT values obtainedfrom header information of the PDCP DATA PDUs. Re-ordering may includeprocessing for delivering, in a case that the COUNT value of the PDCPdata PDU received is the COUNT value of a first PDCP SDU not deliveredto the higher layer yet, the stored PDCP SDUs to the higher layeraccording to the order of COUNT values. In other words, in a case thatthe PDCP data PDUs having the COUNT values smaller than the COUNT valuesof the received PDCP data PDUs have not yet been successfully received(PDCP data PDUs are lost), re-ordering may be processing in which thereceived PDCP data PDUs are converted into the PDCP SDUs and the PDCPSDUs are stored in a re-ordering buffer, and after all of the lost PDCPdata PDUs are received and then converted into the PDCP SDUs, the PDCPSDUs are delivered to the higher layer. In re-ordering, in order todetect loss of the PDCP data PDUs, a re-ordering timer (a timer referredto as t-Reordering described in NPL 11 or NPL 5) may be used. Forre-ordering, a part or all of the following state variables of (A) to(F) may be used:

-   (A) A state variable indicating the COUNT value of the PDCP SDU    expected to be subsequently received on the reception side of the    PDCP entity. The state variable may be a state variable referred to    as RX NEXT described in NPL 11;-   (B) A state variable indicating the sequence number of the PDCP SDU    expected to be subsequently received on the reception side of the    present PDCP entity. The state variable may be a state variable    referred to as Next_PDCP_RX_SN described in NPL 5;-   (C) A state variable indicating the HFN value used for generating    the COUNT value for a received PDCP PDU in the present PDCP entity.    The state variable may be a state variable referred to as RX_HFN    described in NPL 5;-   (D) A state variable indicating the COUNT value of a first PDCP PDU    out of PDCP SDUs that are to be received and have not been delivered    to a higher layer on the reception side of the PDCP entity. The    state variable may be a state variable referred to as RX_DELIV    described in NPL 11;-   (E) A state variable indicating the sequence number of the PDCP PDU    out of the PDCP SDUs that were last delivered to a higher layer on    the reception side of the present PDCP entity. The state variable    may be a state variable referred to as Last_Submitted_PDCP_RX_SN    described in NPL 5;-   (F) A state variable indicating a COUNT value next to the COUNT    value of the PDCP PDU that caused the re-ordering timer to initiate    on the reception side of the PDCP entity. The state variable may be    a state variable referred to as RX_REORO described in NPL 11, or may    be a state variable referred to as Reordering_PDCP_RX_COUNT    described in NPL 5.

Note that in each embodiment of the present invention, in order to makea distinction between the E-UTRA protocol and the NR protocol, the MAC202, the RLC 204, the PDCP 206, and the RRC 208 may be respectivelyreferred to as a MAC for E-UTRA or a MAC for LTE, an RLC for E-UTRA oran RLC for LTE, a PDCP for E-UTRA or a PDCP for LTE, and an RRC forE-UTRA or an RRC for LTE. The MAC 302, the RLC 304, the PDCP 306, andthe RRC 308 may also be referred to as MAC for NR, RLC for NR, RLC forNR, and RRC for NR, respectively. Alternatively, there may bedescriptions using a space such as an E-UTRA PDCP or an LTE PDCP, an NRPDCP, and the like.

As illustrated in FIG. 1 , the eNB 102, the gNB 108, the EPC 104, andthe 5GC 110 may be connected to one another via the interface 112, theinterface 116, the interface 118, the interface 120, and the interface114. Thus, the RRC 208 in FIG. 2 may be replaced with the RRC 308 inFIG. 3 to support various communication systems. The PDCP 206 in FIG. 2may also be replaced with the PDCP 306 in FIG. 3 . The RRC 308 in FIG. 3may include the function of the RRC 208 in FIG. 2 . The PDCP 306 in FIG.3 may be the PDCP 206 in FIG. 2 . In the E-UTRA 100, the NR PDCP may beused as a PDCP even in a case that the UE 122 communicates with the eNB102.

The state transition of the UE 122 in LTE and NR will now be described.The UE 122 connected to the EPC or the 5GC may be in an RRC_CONNECTEDstate in a case that an RRC connection has been established. The statein which the RRC connection has been established may include a state inwhich the UE 122 retains a part or all of UE contexts to be describedlater. The state in which the RRC connection has been established mayinclude a state in which the UE 122 can transmit and/or receive unicastdata. The UE 122 may be in an RRC_INACTIVE state in a case that the RRCconnection is suspended (in a case that the UE 122 is connected to the5GC). Otherwise, the UE 122 may be in an RRC_IDLE state.

Note that the UE 122 connected to the EPC does not have the RRC_INACTIVE state but that the E-UTRAN may initiate suspension of the RRCconnection. In this case, in response to suspension of the RRCconnection, the UE 122 transitions to the RRC_IDLE state while retainingan AS context of the UE and an identity used for resumption(resumeIdentity). In a case that the UE 122 retains the AS context ofthe UE and that the E-UTRAN permits the RRC connection to be resumed andthat the UE 122 needs to transition from the RRC_IDLE state to theRRC_CONNECTED state, the resumption of the RRC connection suspended maybe initiated by the higher layer (e.g., the NAS layer).

In other words, the definition of the suspension may vary between the UE122 connected to the EPC and the UE 122 connected to the 5GC. All or apart of the procedures for the UE 122 to resume from suspension may bedifferent between a case that the UE 122 is connected to the EPC (issuspended in the RRC_IDLE state) and a case that the UE 122 is connectedto the 5GC (is suspended in the RRC_INACTIVE state).

Note that the RRC_CONNECTED state, the RRC_INACTIVE state, and theRRC_IDLE state may be respectively referred to as a connected state(connected mode), an inactive state (inactive mode), and an idle state(idle mode), or may be respectively referred to as an RRC connectedstate (RRC connected mode), an RRC inactive state (RRC inactive mode),and an RRC idle state (RRC idle mode).

The AS context of the UE retained by the UE 122 may be informationincluding all or some of a current RRC configuration, a current securitycontext, a PDCP state including a RObust Header Compression (ROHC)state, a Cell Radio Network Temporary Identifier (C-RNTI) used in aPCell of a connection source, a cell identity (cellIdentity), and aphysical cell identity of the PCell of the connection source. Note thatthe AS context of the UE retained by one or all of the eNB 102 and thegNB 108 may include information identical to the information of the AScontext of the UE retained by the UE 122, or may include informationdifferent from the information included in the AS context of the UEretained by the UE 122.

The security context may be information including all or some of aciphering key at the AS level, a Next Hop parameter (NH), a Next HopChaining Counter parameter (NCC) used to derive an access key for thenext hop, an identifier of a ciphering algorithm at a selected AS level,and a counter used for replay protection.

Next, the handover in LTE and NR will be described. The handover may beprocessing in which the UE 122 in the RRC connected state changes theserving cell. The handover may be performed in a case that the UE 122receives an RRC message indicating handover from the eNB 102 and/or thegNB 108. The RRC message indicating handover may be a message related toreconfiguration of RRC connection including a parameter indicatinghandover (for example, an information element referred to asMobilityControlInfo described in NPL 4, or an information elementreferred to as ReconfigurationWithSync described in NPL 10), or may be amessage indicating movement to a cell of another RAT (for example,MobilityFromEUTRACommand described in NPL 4, or MobilityFromNRCommanddescribed in NPL 10). As a condition that the UE 122 can performhandover, a part or all of a case that AS security is activated, a casethat the SRB2 is established, and a fact that at least one DRB isestablished may be included.

FIG. 4 is a diagram illustrating an example of a flow of a procedure forvarious configurations in the RRC 208 and/or the RRC 308 according toeach embodiment of the present invention. FIG. 4 is an example of a flowin a case that an RRC message is transmitted from the base stationapparatus (eNB 102 and/or gNB 108) to the terminal apparatus (UE 122).

In FIG. 4 , the base station apparatus creates an RRC message (stepS400). The creation of the RRC message in the base station apparatus maybe performed in a case that the base station apparatus distributesbroadcast information (System Information (SI)) or paging information,or in a case that the base station apparatus determines a need to causea particular terminal apparatus to perform processing, for example,configuration related to security, reconfiguration of an RRC connection(processing (establishment, change, release, or the like) of the radioline bearer, processing (establishment, addition, change, release, orthe like) of the cell group, measurement configuration, handoverconfiguration, or the like), release of the RRC connected state, or thelike. The RRC message may be used for a command for handover to adifferent RAT. The RRC message includes information (parameters) forvarious information notifications and configurations. In specificationsrelated to RRC in NPL 4, NPL 10, or the like, the above-describedparameters are referred to as fields and/or information elements, andare notated by using a notation method referred to as Abstract SyntaxNotation One (ASN.1).

In FIG. 4 , the base station apparatus then transmits the RRC messagecreated, to the terminal apparatus (step S402). Then, in a case thatprocessing such as a configuration is necessary in accordance with theRRC message received, the terminal apparatus performs the processing(step S404).

Note that the creation of the RRC message is not limited to the exampledescribed above, and may be performed for other purposes, as describedin NPL 4, NPL 10, and the like.

For example, the RRC message may be used for configuration related toDual Connectivity (DC) or Multi-Radio Dual Connectivity (MR-DC)described in NPL 8.

The Dual Connectivity (DC) may be a technology for performing datacommunication by using radio resources of both cell groups including twobase station apparatuses (nodes), that are a master cell group (MCG)including master nodes (MNs) and a secondary cell group (SCG) includingsecondary nodes (SNs). The master node and the secondary node may be anidentical node (identical base station apparatus). As described in NPL8, the MR-DC may be a technology in which cells of both Radio AccessTechnologies (RATs) of E-UTRA and NR are formed into cell groups foreach RAT, which are assigned to the UE, and in which data communicationis performed by utilizing radio resources of both MCG and SCG, or may beDual Connectivity (DC) using the RAT of NR. In the MR-DC, the masternode may be a base station including primary RRC functions related toMR-DC, for example, functions to add a secondary node, to establish,change, and release an RB, to add, change, and release an MCG, and toperform handover and the like, and the secondary node may be a basestation including some RRC functions, for example, functions to changeand release an SCG, and the like.

In the MR-DC described in NPL 8, the RRC corresponding to the masternode side RAT may be used to configure both the MCG and the SCG. Forexample, in E-UTRA-NR Dual Connectivity (EN-DC) corresponding to theMR-DC in which the EPC 104 is used as a core network and the eNB 102(also referred to as an evolved eNB 102) is used as a master node and inNG-RAN E-UTRA-NR Dual Connectivity (NGEN-DC) corresponding to the MR-DCin which the 5GC 110 is used as a core network and the eNB 102 is usedas a master node, an RRC message for E-UTRA described in NPL 4 may betransmitted and received between the eNB 102 and the UE 122. In thiscase, the RRC message may include NR configuration information describedin NPL 10 as well as LTE (E-UTRA) configuration information. The RRCmessage transmitted from the eNB 102 to the UE 122 may be transmittedfrom the eNB 102 to the UE 122 via the gNB 108. The configuration of thepresent RRC message may be used in E-UTRA/5GC in which the eNB 102(evolved eNB) uses the 5GC as a core network.

In contrast, in the MR-DC described in NPL 8, in NR-E-UTRA DualConnectivity (NE-DC) corresponding to the MR-DC in which the 5GC 110 isused as a core network and the gNB 108 is used as a master node, an RRCmessage for NR described in NPL 10 may be transmitted and receivedbetween the gNB 108 and the UE 122. In this case, the RRC message mayinclude LTE (E-UTRA) configuration information described in NPL 4 aswell as NR configuration information. The RRC message transmitted fromthe gNB 108 to the UE 122 may be transmitted from the gNB 108 to the UE122 via the eNB 102.

Note that the embodiment is not limited to the case of utilization ofthe MR-DC and that the RRC message for E-UTRA transmitted from the eNB102 to the UE 122 may include an RRC message for NR, whereas the RRCmessage for NR transmitted from the gNB 108 to the UE 122 may include anRRC message for E-UTRA.

A network configuration in which the eNB 102 is used as a master nodeand the EPC 104 is used as a core network may be referred to asE-UTRA/EPC. A network configuration in which the eNB 102 is used as amaster node and the 5GC 110 is used as a core network may be referred toas E-UTRA/5GC. A network configuration in which the gNB 108 is used as amaster node and the 5GC 110 is used as a core network may be referred toas NR or NR/5GC. This designation need not be limited to a case wherethe DC is configured. In the case that the DC is not configured, theabove-described master node may refer to a base station apparatus thatcommunicates with the terminal apparatus.

FIG. 7 illustrates an example of an ASN.1 notation representing a fieldand/or an information element related to a radio bearer configurationincluded in a message related to reconfiguration of RRC connection in NRin FIG. 4 . FIG. 8 illustrates an example of an ASN.1 notationrepresenting a field and/or an information element related to a radiobearer configuration included in a message related to reconfiguration ofRRC connection in E-UTRA in FIG. 4 . In an example of ASN.1 illustratedalso in other drawings than FIGS. 7 and 8 according to the embodiment ofthe present invention, <omitted> and <partly omitted> are not part ofthe notation of ASN.1 and mean that other information is omitted. Notethat there may also be omitted information elements in a part whereneither <omitted> nor <partly omitted> is indicated. Note that, in anembodiment of the present invention, the examples of ASN.1 do notcorrectly follow the ASN.1 notation method but represent examples ofparameters of a message for reconfiguration of RRC connection accordingto an embodiment of the present invention and that any other designationand any other notation may be used. The examples of ASN.1 correspond toonly examples related to main information closely associated with anaspect of the present invention in order to avoid complicateddescription. Note that the parameters notated in ASN.1 may all bereferred to as information elements without distinction between fields,information elements, or the like. In an embodiment of the presentinvention, the parameters such as fields and information elementsnotated in ASN.1, the parameters being included in the RRC message, mayalso be referred to as information. Note that the message related toreconfiguration of RRC connection may be an RRC reconfiguration messagein NR or an RRC connection reconfiguration message in E-UTRA.

In FIG. 7 , the information element represented by RadioBearerConfig isan information element related to configurations of radio bearers suchas SRBs or DRBs and include PDCP configuration information elements andSDAP configuration information elements to be described later. Aninformation element represented by SRB-ToAddMod and included in theinformation elements represented by RadioBearerConfig may be informationindicating a signaling radio bearer (SRB) configuration, and may also beinterpreted as an SRB configuration information element or a signalingradio bearer configuration information element. An information elementrepresented by SRB-ToAddModList may be a list of pieces of informationindicating SRB configurations. An information element represented byDRB-ToAddMod and included in the information elements represented byRadioBearerConfig may be information indicating a data radio bearer(DRB) configuration, and may also be interpreted as a DRB configurationinformation element or a data radio bearer configuration informationelement. An information element represented by DRB-ToAddModList may be alist of pieces of information indicating DRB configurations. Note thatany or all of the SRB configurations and the DRB configurations may alsobe interpreted as radio bearer configurations.

An information element included in the SRB configuration informationelements and represented by SRB-Identity is information of SRB identityof an SRB to be added or changed, and may be an identifier that uniquelyidentifies the SRB at each terminal apparatus. The information elementincluded in the SRB configuration information elements and representedby SRB-Identity may also be interpreted as an SRB identity informationelement, a radio bearer identity information element, or a signalingradio bearer identity information element.

An information element included in the DRB configuration informationelements and represented by DRB-Identity is an information of DRBidentity of a DRB to be added or changed, and may be an identifier thatuniquely identifies the DRB at each terminal apparatus. The informationelement included in the DRB configuration information elements andrepresented by DRB-Identity may also be interpreted as a DRB identityinformation element, a radio bearer identity information element, or adata radio bearer identity information element. In the exampleillustrated in FIG. 7 , the DRB identity has an integer value rangingfrom 1 to 32. However, the DRB identity may take another value. For DC,the DRB identity is unique within the scope of the UE 122.

An information element included in the DRB configuration informationelements and represented by cnAssociation may be an information elementindicating whether the EPC 104 or the 5GC 110 is used as a core network,and may also be interpreted as a core network association informationelement. In other words, in a case that the UE 122 is connected to theEPC, the DRB may be associated with an EPS bearer identity informationelement (eps-BearerIdentity) in cnAssociation or with an EPS beareridentity corresponding to the value of the EPS bearer identityinformation element. In a case that the UE 122 is connected to the 5GC110, the DRB may be associated with an SDAP entity configured inaccordance with an SDAP configuration information element (sdap-Config)described below, or a PDU session information element described belowand included in the SDAP configuration information element, or a PDUsession identity corresponding to the value of the PDU sessioninformation element, or a PDU session indicated by the PDU sessioninformation element. In other words, the information represented bycnAssociation may include an EPS bearer identity information element(eps-BearerIdentity) in a case that the EPC 104 is used as a corenetwork, such as in a case of using EN-DC, and may include aninformation element (sdap-Config) indicating an SDAP configuration in acase that the 5GC 110 is used as a core network, in other words, in acase of not using EN-DC.

The information element represented by sdap-Config may be informationrelated to a configuration or reconfiguration of the SDAP entity thatdetermines a mapping method between the QoS flow and the DRB in a casethat the 5GC 110 is used as a core network, and may also be interpretedas an SDAP configuration information element.

A field or an information element included in the SDAP configurationinformation elements and represented by pdu-session or PDU-SessionID maybe the PDU session identity of a PDU session described in NPL 2 and towhich the QoS flow mapped to the radio bearer corresponding to the valueof the radio bearer identity information element belongs, the radiobearer identity information element being included in the DRBconfiguration information elements including the present SDAPconfiguration information element, and may also be interpreted as a PDUsession identity information element. The value of the PDU sessionidentity information element may be an integer that is not negative. Ateach of the terminal apparatuses, multiple DRB identities may correspondto one PDU session identity.

An information element included in the SDAP configuration informationelements and indicated by mappedQoS-FlowsToAdd may be informationindicating a list of QoS flow identity (QFI) information elementsdescribed below of QoS flows to be mapped to or additionally mapped tothe radio bearer corresponding to the value of the radio bearer identityinformation element included in the DRB configuration informationelements including the present SDAP configuration information elements,and may also be interpreted as an added QoS flow information element.The QoS flow described above may be a QoS flow of a PDU sessionindicated by the PDU session information element included in the presentSDAP configuration information elements.

An information element included in the SDAP configuration informationelements and indicated by mappedQoS-FlowsToRelease may be informationindicating a list of QoS flow identity (QFI) information elementsdescribed below of QoS flows from which a mapping relationship is to bereleased and which are included in the QoS flows mapped to the radiobearer corresponding to the value of the radio bearer identityinformation element included in the DRB configuration informationelements including the present SDAP configuration information elements,and may also be interpreted as a released QoS flow information element.The QoS flow described above may be a QoS flow of a PDU sessionindicated by the PDU session information element included in the presentSDAP configuration information elements.

An information element indicated by QFI may be a QoS flow identitydescribed in NPL 2 and uniquely identifying a QoS flow, and may bereplaced with a QoS flow identity information element. The value of theQoS flow identity information element may be a non-negative integer. Thevalue of the QoS flow identity information element may be unique to thePDU session.

The SDAP configuration information elements may include, in addition tothe above-described information elements, an uplink header informationelement indicating whether an uplink SDAP header is present in uplinkdata transmitted via the configured DRB, a downlink header informationelement indicating whether a downlink SDAP header is present in downlinkdata received via the configured DRB, a default bearer informationelement indicating whether the configured DRB is a default radio bearer(default DRB), and the like.

Information elements included in the SRB configuration informationelements and the DRB configuration information elements and representedby pdcp-Config or PDCP-Config may be information elements used toestablish or change the PDCP 306 for the SRB and/or the DRB and relatedto the configuration of an NR PDCP entity, and may also be interpretedas PDCP configuration information elements. The information elementsrelated to the configuration of the NR PDCP entity include aninformation element indicating the size of an uplink sequence number, aninformation element indicating the size of a downlink sequence number,an information element indicating a profile of header compression(RObust Header Compression (RoHC)), a re-ordering timer informationelement, and the like.

An information element represented by DRB-ToReleaseList and included inthe information elements represented by RadioBearerConfig may includeinformation indicating one or more DRB identities to be released.

In FIG. 8 , an information element represented byRadioResourceConfigDedicated may be an information element used forconfiguration, change, release, or the like of the radio bearer. Aninformation element represented by SRB-ToAddMod and included in theinformation elements represented by RadioResourceConfigDedicated may beinformation indicating a signaling radio bearer (SRB) configuration, andmay also be interpreted as an SRB configuration information element or asignaling radio bearer configuration information element. An informationelement represented by SRB-ToAddModList may be a list of piece ofinformation indicating SRB configurations. An information elementrepresented by DRB-ToAddMod and included in the information elementsrepresented by RadioResourceConfigDedicated may be informationindicating a data radio bearer (DRB) configuration, and may also beinterpreted as a DRB configuration information element or a data radiobearer configuration information element. An information elementrepresented by DRB-ToAddModList may be a list of pieces of informationindicating DRB configurations. Note that any or all of the SRBconfigurations and the DRB configurations may also be interpreted asradio bearer configurations.

An information element included in the SRB configuration informationelements and represented by SRB-Identity is information of SRB identityof an SRB to be added or changed, and may be an identifier that uniquelyidentifies the SRB at each terminal apparatus. The information elementincluded in the SRB configuration information elements and representedby SRB-Identity may also be interpreted as an SRB identity informationelement, a radio bearer identity information element, or a signalingradio bearer identity information element. An information elementrepresented by SRB-Identity in FIG. 8 may be an information elementhaving a role identical to the role of the information elementrepresented by SRB-Identity in FIG. 7

An information element included in the DRB configurations andrepresented by DRB-Identity may be information of DRB identity of a DRBto be added or changed and may be a DRB identity uniquely identifying,at each terminal apparatus, the DRB. The information element included inthe DRB configurations and represented by DRB-Identity may also beinterpreted as a DRB identity information element, a radio beareridentity information element, or a data radio bearer identityinformation element. In the example illustrated in FIG. 8 , the DRBIdentity has an integer value ranging from 1 to 32. However, the DRBidentity may take another value. The information element represented byDRB-Identity in FIG. 8 may be an information element having a roleidentical to the role of the information element represented byDRB-Identity in FIG. 7 .

An information element included in the DRB configuration informationelements and represented by eps-BearerIdentity may be an EPS beareridentity uniquely identifying an EPS bearer at each terminal apparatus.The information element represented by eps-BearerIdentity may bereferred to as an EPS bearer identity information element. In theexample illustrated in FIG. 8 , the EPS bearer Identity has an integervalue ranging from 1 to 15. However, the EPS bearer identity may takeanother value. The information element represented by eps-BearerIdentityin FIG. 8 may be an information element having a role identical to therole of the information element represented by eps-BearerIdentity inFIG. 7 At each terminal apparatus, the EPS bearer identities maycorrespond to the DRB identities on a one-to-one basis.

An information element included in the SRB configuration informationelements and the DRB configuration information elements and representedby pdcp-Config or PDCP-Config may be an information element related tothe configuration of an E-UTRA PDCP entity and used to establish orchange the PDCP 206 for the SRB and/or for the DRB, and may also beinterpreted as a PDCP configuration information element. The informationelements related to the configuration of the E-UTRA PDCP entity mayinclude an information element indicating the size of the sequencenumber, an information element indicating the profile of headercompression (RObust Header Compression (RoHC)), a re-ordering timerinformation element, and the like.

Some or all of the information elements illustrated in FIG. 7 or FIG. 8may be optional. In other words, the information elements illustrated inFIG. 7 or FIG. 8 may be included in a message related to thereconfiguration of RRC connection depending on requirements orconditions. The message related to the reconfiguration of RRC connectionmay include an information element meaning that a full configuration isto be applied, in addition to an information element related to theconfiguration of the radio bearer. The information element meaning thatthe full configuration is to be applied may be represented by aninformation element name such as fullConfig, and true, enable, or thelike may be used to indicate application of the full configuration.

An information element represented by DRB-ToReleaseList and included inthe information elements represented by RadioResourceConfigDedicated mayinclude information indicating one or more DRB identities to bereleased.

In a case that RRC connection is established, in a case that the RRCconnection is re-established, or in a case of handover, one serving cellprovides mobility information for the NAS. In a case that the RRCconnection is re-established or in a case of handover, one serving cellprovides a security input. The serving cell may be referenced as aprimary cell (PCell). Depending on the capability of the terminalapparatus, one or multiple serving cells (secondary cells, SCells) maybe additionally configured together with the primary cell.

A set of serving cells including two subsets may be configured for theterminal apparatus. The two subsets may include a cell group (mastercell group) including one or multiple serving cells including theprimary cell (PCell), and one or multiple cell groups (secondary cellgroups) each including one or multiple serving cells including a primarysecondary cell (PSCell) and no primary cell. The primary secondary cellmay be a cell configured with a PUCCH resource. Note that the PCelland/or the PSCell may be referred to as a special cell (SpCell).

Various embodiments of the present invention will be described based onthe foregoing description. Note that, for each of the steps ofprocessing omitted in the following description, each of the steps ofprocessing described above may be applied.

FIG. 5 is a block diagram illustrating a configuration of the terminalapparatus (UE 122) according to each embodiment of the presentinvention. Note that FIG. 5 illustrates only the main components closelyrelated to an aspect of the present invention in order to avoidcomplexity of description

The UE 122 illustrated in FIG. 5 includes a receiver 500 configured toreceive an RRC message and the like from a base station apparatus, aprocessing unit 502 configured to perform processing in accordance withany or all of pieces of configuration information such as variousinformation elements (IEs), various fields, and various conditionsincluded in the message received, and a transmitter 504 configured totransmit the RRC message and the like to the base station apparatus. Theabove-described base station apparatus may be the eNB 102 or the gNB108. The processing unit 502 may include some or all of the functions ofvarious layers (e.g., a physical layer, a MAC layer, an RLC layer, aPDCP layer, an RRC layer, and an NAS layer). In other words, theprocessing unit 502 may include some or all of a physical layerprocessing unit, a MAC layer processing unit, an RLC layer processingunit, a PDCP layer processing unit, an RRC layer processing unit, and anNAS layer processing unit.

FIG. 6 is a block diagram illustrating a configuration of the basestation apparatus according to each embodiment of the present invention.Note that FIG. 6 illustrates only the main components closely related toone aspect of the present invention in order to avoid complexity ofdescription. The above-described base station apparatus may be the eNB102 or the gNB 108.

The base station apparatus illustrated in FIG. 6 includes a transmitter600 configured to transmit an RRC message and the like to the UE 122, aprocessing unit 602 configured to create an RRC message including any orall of pieces of configuration information such as various informationelements (IEs), various fields, and various conditions and to transmitthe RRC message to the UE 122 to cause the processing unit 502 of the UE122 to perform processing, and a receiver 604 configured to receive theRRC message and the like from the UE 122. The processing unit 602 mayinclude some or all of the functions of various layers (e.g., thephysical layer, the MAC layer, the RLC layer, the PDCP layer, the RRClayer, and the NAS layer). In other words, the processing unit 602 mayinclude some or all of the physical layer processing unit, the MAC layerprocessing unit, the RLC layer processing unit, the PDCP layerprocessing unit, the RRC layer processing unit, and the NAS layerprocessing unit.

With reference to FIG. 9 to FIG. 11 , an overview of operations of MBMStransmission/reception using the SC-PTM will be described. Note that anMBMS, an MBMS service, and an MBMS session, which are terms to be usedin the following description, may be terms having the same meanings andmay be replaced with each other.

FIG. 9 is a diagram illustrating a flow of a procedure for configurationof MBMS reception using the SC-PTM. FIG. 10 is a diagram illustrating anexample of ASN.1 notation representing fields and/or informationelements included in System Information Block Type 20 (SIB20) of FIG. 9. FIG. 11 is a diagram illustrating an example of ASN.1 notationrepresenting fields and/or information elements included in an SC-PTMconfiguration message (SCPTMConfiguration) of FIG. 9 .

As illustrated in FIG. 9 , the processing unit 602 of the eNB 102creates the System Information Block type 20 (SIB20) being an RRCmessage, and transmits the SIB20 from the transmitter 600 to the UE 122via the BCCH. The receiver 500 of the UE 122 receives the SLB20. (StepS900).

As described in NPL 4, the SIB20 includes information necessary foracquisition of control information (specifically, the SC-MCCH) relatedto transmission of the MBMS using the SC-PTM. For example, the SIB20includes a part or all of fields, such as a field represented bysc-mcch-ModificationPeriod indicating a period for which details of theSC-MCCH may be changed, a field represented by sc-mcch-RepetitionPeriodindicating a transmission (retransmission) time interval of the SC-MCCHwith the number of radio frames, a field represented by sc-mcch-Offsetindicating an offset of the radio frame in which the SC-MCCH isscheduled, a field represented by sc-mcch-FirstSubframe indicating thesubframe in which the SC-MCCH is scheduled, and a field represented bysc-mcch-duration indicating a period of the subframe in which theSC-MCCH is scheduled, and/or information elements.

Next, the processing unit of the eNB 102 creates an SC-PTM configurationmessage (SCPTM Configuration) being an RRC message, and transmits theSC-PTM configuration message from the transmitter 600 via the SC-MCCH.The receiver 500 of the UE 122 receives SC-PTM configurationinformation, based on the configuration of the SIB20. In the physicallayer, a Single Cell RNTI (SC-RNTI) is used for transmission of theSC-MCCH. (Step S902).

As described in NPL 4, the SC-PTM configuration information includescontrol information that can be applied to MBMS reception. For example,the SC-PTM configuration information includes a part or all of fields,such as a field represented by sc-mtch-InfoList including theconfiguration of each SC-MTCH in a cell for transmitting the informationand a field represented by scptm-NeighbourCellList being a list ofneighboring cells that provide the MBMS, and/or information elements.

sc-mtch-InfoList includes one or multiple information elementsrepresented by SC-MTCH-Info. Each SC-MTCH-Info includes a part or all offields, such as a field represented by mbmsSessionInfo being informationof the MBMS session, a field represented by g-RNTI being a Radio NetworkTemporary Identifier (RNTI) for identifying a multicast group(specifically, the SC-MTCH addressed to a specific group), a fieldrepresented by sc-mtch-schedulingInfo being DRX information for SC-MTCH,and a field represented by sc-mtch-neighbourCell being information of aneighboring cell from which the MBMS session can be received using theSC-MTCH. mbmsSessionInfo includes a part or all of fields, such as afield represented by tmgi being a Temporary Mobile Group Identity(TMGI), which is an identifier for identifying an MBMS bearer service,described in NPL 15 and the like and a field represented by sessionIdbeing an identifier of the MBMS session described in NPL 15 and thelike.

In order to initiate reception of the MBMS session in which theprocessing unit 502 of the UE 122 is interested, the processing unit 502may perform Single Cell MBMS Point to Multipoint Radio Bearer (SC-MRB)establishment processing, the SC-MRB being a radio bearer for MBMSsession reception using the SC-PTM (Step S904). For example, the SC-MRBestablishment processing may be started in a case of initiating the MBMSsession, a case that the UE 122 enters a cell where the MBMS service inwhich the UE 122 is interested is provided via the SC-MRB, a case ofstarting to take an interest in the MBMS service, a case that arestriction on UE capability that has restricted reception of the MBMSservice is removed, and the like. The SC-MRB establishment processingmay be performed in a case that the UE 122 is in the RRC_IDLE state, ormay be performed in a case that the UE 122 is in the RRC_CONNECTEDstate. In a case of performing the SC-MRB establishment processing, theprocessing unit 502 of the UE 122 may perform a part or all of thefollowing processing of (A) to (D):

-   (A) establish the RLC entity according to a default configuration of    the SC-MCCH and the SC-MTCH;-   (B) configure an SC-MTCH logical channel to be applied to the SC-MRB    to be established, and instruct the MAC entity so as to receive the    MBMS session according to the SC-PTM configuration message for a    cell in which the SC-PTM configuration message is received;-   (C) configure the physical layer for the SC-MRB to be established,    based on sc-mtch-InfoList described above;-   (D) notify a higher layer of tmgi and sessionId corresponding to the    established SC-MRB and thereby notify the higher layer of    establishment of the SC-MRB.

The processing unit 502 of the UE 122 receives the MBMS session via theestablished SC-MRB according to the SC-PTM configuration message (StepS906). Before receiving the MBMS session, the processing unit 502 of theUE 122 may create an MBMS interest notification message(MBMSInterestIndication), which is for notifying the eNB 102 that the UE122 is to receive or is interested in receiving the MBMS service via theSC-MRB, and transmit the MBMS interest notification message from thetransmitter 504 to the eNB 102 (not illustrated). The MBMS interestnotification message may include information as to whether to prioritizeMBMS service reception over unicast reception. The MBMS interestnotification message may be transmitted after the SIB20 is received, ina case of transition to the RRC_CONNECTED state, or after transition tothe RRC_CONNECTED state. The MBMS interest notification message may betransmitted in a case that the SIB20 is received in handover, or may betransmitted in a case that the SIB20 is received in re-establishment ofthe RRC connection.

The processing unit 502 of the UE 122 may perform SC-MRB releaseprocessing in order to stop reception of the MBMS session (Step S908).For example, the SC-MRB release processing may be started in a case ofstopping the MBMS session being received, a case of leaving from a cellin which the SC-MRB is established, a case that the interest in the MBMSservice is lost, a case that reception of the MBMS service is restricteddue to the restriction on the UE capability, and the like. The SC-MRBrelease processing may be performed in a case that the UE 122 is in theRRC_IDLE state, or may be performed in a case that the UE 122 is in theRRC_CONNECTED state. In a case of performing the SC-MRB releaseprocessing, the processing unit 502 of the UE 122 may perform a part orall of the following processing of (A) to (B):

-   (A) release a physical layer configuration with the RLC entity of    the SC-MRB to be released and the MAC related thereto;-   (B) notify a higher layer of tmgi and sessionId corresponding to the    released SC-MRB and thereby notify the higher layer of release of    the SC-MRB.

In the above, an overview of operations related to the configuration ofMBMS reception using the SC-PTM has been described. As described in NPL4 and the like, MBMS transmission/reception using the MBSFN has alsobeen standardized in addition to MBMS transmission from the base stationapparatus/MBMS reception in the terminal apparatus using the SC-PTM(hereinafter referred to as MBMS transmission/reception). However, theMBMS transmission/reception using the SC-PTM and the MBMStransmission/reception using the MBSFN described in NPL 4 use E-UTRA astheir RATs. Multicast Broadcast Service (MBS) transmission/receptionusing NR as its RAT has not yet been standardized.

With reference to FIG. 12 to FIG. 13 , an example of operations relatedto a configuration of MBS reception according to an embodiment of thepresent invention will be described. Note that an MBS, an MBS service,and an MBS session, which are terms to be used in an embodiment of thepresent invention, may be terms having the same meanings and may bereplaced with each other. The MBS, the MBS service, and the MBS session,which are terms to be used in an embodiment of the present invention,may be terms having the same meanings as the MBMS, the MBMS service, andthe MBMS session described in NPL 4 and the like. In an embodiment ofthe present invention, the MBS Radio Bearer (MRB) may be a radio bearerestablished in the UE 122 for MBS reception. The MRB may be a radiobearer established in the gNB 108 for MBS transmission. In an embodimentof the present invention, the radio bearer for MBS receptions isdescribed using the term “MRB”, but other terms may be used. In anembodiment of the present invention, the MRB may include an MRB forreceiving and/or transmitting the MBS on a Point-to-Multipoint basis, oran MRB for receiving and/or transmitting the MBS on a Point-to-Pointbasis. The receiving and/or transmitting an MBS on a point-to-multipointbasis may be receiving and/or transmitting an MBS via the multicastlogical channel such as the MTCH and the SC-MTCH. The receiving and/ortransmitting an MBS on a point-to-point basis may be receiving and/ortransmitting an MBS via the dedicated user data logical channel such asthe DTCH. In an embodiment of the present invention, an operation forswitching a mode of receiving and/or transmitting an MBS on apoint-to-multipoint basis to a mode of receiving and/or transmitting theMBS on a point-to-point basis is involved. In an embodiment of thepresent invention, an operation for switching the mode of receivingand/or transmitting an MBS on a point-to-point basis to the mode ofreceiving and/or transmitting the MBS on a point-to-multipoint basis isinvolved. Note that, in an embodiment of the present invention, thereceiving and/or transmitting an MBS in one-to-many may be interpretedas receiving and/or transmitting an MBS on a point-to-multipoint basisor receiving and/or transmitting an MBS in multicast. In an embodimentof the present invention, the receiving and/or transmitting an MBS inone-to-one may be interpreted as receiving and/or transmitting an MBS ona point-to-point basis or receiving and/or transmitting an MBS inunicast.

FIG. 12 is a diagram illustrating an example illustrating aconfiguration of the SDAP sublayer according to an embodiment of thepresent invention. (A) of FIG. 12 is an example in which an RLC-ServiceAccess Point (RLC-SAP) is present between the SDAP sublayer and the RLCsublayer. In the example of (A) of FIG. 12 , in the UE 122, data of theMBS session received via the MRB may be delivered to the SDAP entity asthe RLC SDU in the RLC entity of the MRB. In the example of FIG. 12(A),in the gNB 108, regarding data of the MBS session transmitted from thecore network, in the SDAP entity of the gNB 108, the QoS flow linked tothe data of the MBS session and the MRB may be mapped to each other, andthis may be submitted to the RLC entity of the mapped MRB as the SDAPPDU.

(B) of FIG. 12 is an example in which a PDCP-Service Access Point(PDCP-SAP) is present between the SDAP sublayer and the PDCP sublayer.In the example of (B) of FIG. 12 , in the UE 122, data of the MBSsession received via the MRB may be delivered to the PDCP entity of theMRB as the RLC SDU in the RLC entity of the MRB. The PDCP entity towhich the RLC SDU is delivered may perform no processing on thedelivered RLC SDU, that is, the PDCP PDU, and directly deliver it to theSDAP entity as the PDCP SDU. In the example of FIG. 12(B), in the gNB108, regarding data of the MBS session transmitted from the corenetwork, in the SDAP entity of the gNB 108, the QoS flow linked to thedata of the MBS session and the MRB may be mapped to each other, andthis may be submitted to the PDCP entity of the mapped MRB as the SDAPPDU. The PDCP entity to which the SDAP PDU is delivered may perform noprocessing on the delivered SDAP PDU, that is, the PDCP SDU, anddirectly deliver it to the RLC entity of the MRB as the PDCP PDU. Inother words, in the example of FIG. 12(B), the PDCP entity may bepresent as a transparent entity that performs no processing. In theexample of FIG. 12(B), the PDCP entity may be present as an entity thatperforms a part of processing of the PDCP sublayer.

Note that “to be linked” may be interpreted as “to be bundled”, or maybe interpreted as other similar terms. “To be associated” may beinterpreted as “to be mapped”, or may be interpreted as other similarterms.

Here, a relationship between the MRB, the SDAP entity, and the PDUsession according to an embodiment of the present invention will bedescribed. The SDAP entity associated with the MRB may be associatedwith one or multiple DRBs. In other words, the PDU session and/or theSDAP entity may be established and/or configured in common to the MBSservice and the unicast service. One PDU session may correspond to theMBS service and the unicast service, and provide the MBS service and/orthe unicast service. One SDAP entity common to the MBS service and theunicast service may be established and/or configured for one PDUsession. In a case that one PDU session corresponds to the MBS serviceand the unicast service and provides the MBS service and/or the unicastservice, the SDAP entity associated with the MRB may be for the MBSservice, and may not be associated with the DRB for the unicast service.Each of one SDAP entity for the MBS service (for MRB) and one SDAPentity for the unicast service (for DRB) may be established and/orconfigured for one PDU session. The PDU session for the MBS service maybe present separately from the PDU session for the unicast service. OneSDAP entity for the MBS service may be established and/or configured forthe PDU session for the MBS service. The SDAP entity need not beestablished and/or configured for the PDU session for the MBS service.In a case that the SDAP entity is not established and/or configured forthe PDU session for the MBS service, the QoS flow and the MRB may not bemapped to each other in the gNB. In the case that one PDU sessioncorresponds to the MBS service and the unicast service and provides theMBS service and/or the unicast service, at least one MRB and/or at leastone DRB may be established for the PDU session. At least one MRB may beestablished for the PDU session for the MBS service. The SDAP entityassociated with the MRB may be established and/or configured in a casethat the UE 122 transitions from the RRC_IDLE state to the RRC CONNECTEDstate, or in a case that the UE 122 transitions from the RRC_INACTIVEstate to the RRC_CONNECTED state. The SDAP entity associated with theMRB may be established and/or configured in a case that the UE 122 is inthe RRC_INACTIVE state and/or the RRC_CONNECTED state. Note that otherterms than the PDU session may be used to refer to the PDU session forthe MBS service.

FIG. 13 is a diagram illustrating an example of a flow of a procedurefor configuration of MBS reception in NR according to an embodiment ofthe present invention. Note that, in the present embodiment, parametersmay refer to fields and/or information elements in ASN.1.

As illustrated in FIG. 13 , in order to broadcast information necessaryfor acquisition of control information related to the MBS transmission,the processing unit 602 of the gNB 108 may create a first SystemInformation Block (SIB) being one of the RRC messages, and transmit thefirst SIB from the transmitter 600 to the UE 122. The receiver 500 ofthe UE 122 receives the first SIB. (Step S900). Note that the first SIBmay be transmitted via the BCCH logical channel or another logicalchannel. The information necessary for acquisition of controlinformation related to the MBS transmission may be information relatedto a Multicast Control Channel (MCCH) logical channel. The MCCH may be apoint-to-multipoint downlink channel for transmitting MBS controlinformation and/or MBS configuration information and/or MBS informationfor one or multiple Multicast Traffic Channel (MTCH) logical channelsfrom the gNB 108 to the UE 122. The MTCH may be a point-to-multipointdownlink channel for transmitting data of the MBS from the gNB 108 tothe UE 122. The MCCH may be a multicast control channel. The MTCH may bea multicast traffic channel. The MTCH may be used by the UE 122 only ina case that the UE 122 receives the MBS. Note that other terms may beused to refer to the MCCH, such as an MBS-MCCH and an NR-MCCH. Otherterms may be used to refer to the MTCH, such as an MBS-MTCH and anNR-MTCH. The MCCH may be mapped to a Multicast Channel (MCH) being adownlink transport channel, or may be mapped to a Downlink SharedChannel (DL-SCH) being a downlink transport channel. The MTCH may bemapped to a Multicast Channel (MCH) being a downlink transport channel,or may be mapped to a Downlink Shared Channel (DL-SCH) being a downlinktransport channel. The MBS control information and/or MBS configurationinformation and/or MBS information for one or multiple MTCH logicalchannels may be included in the SIB, or may be included in a second SIBother than the first SIB.

For example, the first SIB may include a part or all of parameters, suchas a parameter indicating a period for which details of the MCCH may bechanged, a parameter related to a transmission (retransmission) timeinterval of the MCCH, a parameter indicating an offset of the radioframe in which the MCCH is scheduled, a parameter indicating thesubframe in which the MCCH is scheduled, and a parameter indicating aperiod of the subframe in which the MCCH is scheduled. Note that theparameter related to the transmission (retransmission) time interval ofthe MCCH may be represented by the number of radio frames.

Next, the processing unit of the gNB 108 may create an RRC message to betransmitted on the MCCH, and transmit the RRC message from thetransmitter 600. The receiver 500 of the UE 122 may receive the RRCmessage transmitted on the MCCH, based on the configuration of the SIB.For the transmission of the MCCH, a dedicated Radio Network TemporaryIdentifier (RNTI) for identifying the MCCH transmission may be used. Asa value of the dedicated RNTI for identifying the MCCH transmission, aspecific value may be used or a value may be configured by the SIB (stepS1302). In an embodiment of the present invention, a message name of MBSconfiguration information message is used to refer to the RRC message tobe transmitted on the MCCH, but other message names may be used.

The MBS configuration information may include control information thatcan be applied to MBS reception. For example, the MBS configurationinformation may include a part or all of fields, such as a parameterrelated to information of the MBS session, a parameter indicating theRNTI for identifying a multicast group (MTCH addressed to a specificgroup), a parameter indicating a logical channel identifier, a parameterrelated to DRX information for the MTCH, and a parameter indicating alist of neighboring cells that provide the same MBS. For example, theparameter related to information of the MBS session may include a partor all of parameters, such as a parameter indicating a Temporary MobileGroup Identity (TMGI), described in NPL 15, which is an identifier foridentifying the MBS (or MBMS) bearer service, a parameter indicating aSession ID, described in NPL 15 and the like, which is an identifier ofthe MBS (or MBMS) session, a parameter indicating the PDU session towhich the MBS (or MBMS) bearer service and/or the MBS session belongs,and a parameter indicating the QoS flow used for the MBS (or MBMS)bearer service and/or the MBS session. A part or all of the MBSconfiguration information may be included in the first SIB, may beincluded in the second SIB, or may be included in a third SIB other thanthe first and second SIBs.

Note that a part or all of the multiple parameters included in the MBSconfiguration information may be included in a form of a list. Theparameters included in the form of a list may be present for each MTCH(or each MBS service) in a cell in which the MCCH is transmitted. Theparameter indicating the list of neighboring cells that provide the sameMBS may include a parameter indicating a list of neighboring cells thatprovide the same MBS via the MTCH and/or the MRB, or may include aparameter indicating a list of neighboring cells that provide the sameMBS via the unicast, and/or the DTCH, and/or the DRB. The parameterindicating the PDU session may be a PDU session ID described in NPL 2and the like. The parameter indicating the PDU session and/or theparameter indicating the QoS flow may be included in the parameterindicating the SDAP configuration.

The MBS reception and/or transmission may be performed via the MRB. TheMBS reception and/or transmission may be performed via the MRB forreceiving and/or transmitting the MBS on a point-to-multipoint basis.The MBS reception and/or transmission may be performed via the MRB forreceiving and/or transmitting the MBS on a point-to-point basis. The MBStransmission and/or transmission may be performed via the DRB. In thecase that the MRB reception and/or transmission may be performed via theMRB for receiving and/or transmitting the MBS on a point-to-point basis,the reception and/or transmission may be performed via the DTCH. In thecase that the MRB reception and/or transmission is performed via theDRB, the reception and/or transmission may be performed via the DTCH.

In order to initiate reception of the MBS session in which theprocessing unit 502 of the UE 122 is interested, the processing unit 502may perform MRB establishment processing (Step S1304). For example, theMRB establishment processing may be started based on a case ofinitiating the MBS session, a case that the UE 122 enters a cell wherethe MBS service in which the UE 122 is interested is provided via theMRB, a case of starting to take an interest in the MBS service, a casethat a restriction on UE capability that has restricted reception of theMBS service is removed, and the like. The MRB establishment processingmay be performed in a case that the UE 122 is in the RRC_IDLE state, maybe performed in a case that the UE 122 is in the RRC_INACTIVE state, ormay be performed in a case that the UE 122 is in the RRC_CONNECTEDstate. In a case of performing the MRB establishment processing, theprocessing unit 502 of the UE 122 may perform a part or all of thefollowing processing of (A) to (G). Note that the processing of (A) maybe performed in a case that the UE 122 is in the RRC_CONNECTED stateand/or the RRC_INACTIVE state. Note that the processing of (F) may beperformed in a case that the UE 122 is in the RRC_CONNECTED state, ormay be performed in a case that the UE 122 is in the RRC_CONNECTED stateand/or the RRC_INACTIVE state. The processing of (F) may be performed ina case that the UE 122 has transitioned from the RRC_IDLE state and/orthe RRC_INACTIVE state to the RRC_CONNECTED state:

-   (A) establish and/or configure the SDAP entity in a case that the    SDAP entity is not present in the PDU session corresponding to the    parameter indicating the PDU session included in the MBS    configuration;-   (B) establish the PDCP entity according to a default configuration    related to MRB establishment or according to a configuration    received from the base station;-   (C) establish the RLC entity according to a default configuration    related to MRB establishment or according to a configuration    received from the base station;-   (D) configure the MTCH logical channel to be applied to the MRB to    be established according to a default configuration or according to    a configuration received from the base station, and instruct the MAC    entity so as to receive the MBS session desired to be received;-   (E) configure the physical layer for the MRB to be established,    based on the received MBS configuration;-   (F) associate the SDAP entity and the established MRB;-   (G) notify a higher layer of information including a part or all of    a TMGI, a Session ID, a PDU session ID, and a QoS flow corresponding    to the established MRB and thereby notify the higher layer of    establishment of the MRB.

Note that the MRB may be an MRB for receiving and/or transmitting theMBS on a point-to-multipoint basis, or an MRB for receiving and/ortransmitting the MBS on a point-to-point basis described above.

Note that, in step S1304 described above, the MRB establishmentprocessing may be started based on receiving or having received an RRCmessage indicating establishing the MRB from the gNB 108. The MRBestablishment processing may be started based on receiving or havingreceived an RRC message including a part or all of session informationof the MBS session of interest via the DCCH logical channel from the gNB108. The MRB establishment processing may be started based on receivingor having received an RRC message including a part or all of sessioninformation of the MBS session of interest via the DCCH logical channelfrom the gNB 108, and based on that the MRB corresponding to the part orall of the session information of the MBS session of interest includedin the RRC message is not established. The MRB establishment processingmay be started based on initiating receiving the MBS on apoint-to-multipoint basis. The MRB establishment processing may bestarted based on receiving an MBS establishment indication from thehigher layer, an indication of initiating receiving the MBS on apoint-to-multipoint basis, or the like. The RRC message indicatingestablishing the MRB may include a part or all of the sessioninformation of the MBS session. The part or all of the sessioninformation of the MBS session may be information including some or allof a TMGI, a Session ID, a PDU session ID, and a QoS flow correspondingto the MBS. The MRB establishment processing may be started based onreceiving a control information element that means initiating receivingthe MBS session of interest from the gNB 108. The control informationelement that means initiating receiving the MBS session of interest mayinclude RNTI information and/or logical channel identifier used forreceiving the MBS session of interest.

Note that, in step S1304 described above, MRB resume processing may beperformed instead of the MRB establishment processing. The MRB resumeprocessing may be processing for resuming the MRB that has beensuspended. For example, the MRB resume processing may be started basedon a case of initiating the MBS session, a case that the UE 122 enters acell where the MBS service in which the UE 122 is interested is providedvia the MRB, a case of starting to take an interest in the MBS service,a case that a restriction on UE capability that has restricted receptionof the MBS service is removed, and the like. The MRB resume processingmay be performed in a case that the UE 122 is in the RRC_IDLE state, maybe performed in a case that the UE 122 is in the RRC_INACTIVE state, ormay be performed in a case that the UE 122 is in the RRC_CONNECTEDstate. In performing the MRB resume processing, information including apart or all of a TMGI, a Session ID, a PDU session ID, and a QoS flowcorresponding to the resumed MRB may be notified to the higher layer.Note that the MRB may be an MRB for receiving and/or transmitting theMBS on a point-to-multipoint basis, or an MRB for receiving and/ortransmitting the MBS on a point-to-point basis described above.

Note that, in step S1304 described above, the MRB resume processing maybe started based on receiving or having received an RRC messageindicating resuming the MRB from the gNB 108. The MRB resume processingmay be started based on receiving or having received an RRC messageincluding a part or all of session information of the MBS session ofinterest via the DCCH logical channel from the gNB 108. The MRB resumeprocessing may be started based on receiving or having received an RRCmessage including a part or all of session information of the MBSsession of interest via the DCCH logical channel from the gNB 108, andbased on that the MRB corresponding to the part or all of the sessioninformation of the MBS session of interest included in the RRC messageis suspended. The MRB resume processing may be started based oninitiating receiving the MBS on a point-to-multipoint basis. The MRBresume processing may be started based on receiving an MBS resumeindication from the higher layer, an indication of initiating receivingthe MBS on a point-to-multipoint basis, or the like. The RRC messageindicating resuming the MRB may include a part or all of the sessioninformation of the MBS session. The part or all of the sessioninformation of the MBS session may be information including some or allof a TMGI, a Session ID, a PDU session ID, and a QoS flow correspondingto the MBS. The MRB resume processing may be started based on receivinga control information element that means initiating receiving the MBSsession of interest from the gNB 108. The control information elementthat means initiating receiving the MBS session of interest may includeRNTI information and/or logical channel identifier used for receivingthe MBS session of interest.

The processing unit 502 of the UE 122 receives the MBS session via theestablished or resumed MRB according to the PTM configuration message(Step S1306). Before receiving the MBS session, the processing unit 502of the UE 122 may create an RRC message for notifying the gNB 108 thatthe UE 122 is to receive or is interested in receiving the MBS servicevia the MRB, and transmit the RRC message from the transmitter 504 tothe eNB 102 (not illustrated). Note that, in an embodiment of thepresent invention, a message name of MBS interest notification message(MBSInterestIndication) is used to refer to the RRC message fornotifying the gNB 108 that the UE 122 is to receive or is interested inreceiving the MBS service via the MRB, but other message names may beused The MBS interest notification message may include information as towhether to prioritize MBS service reception over unicast reception. TheMBS interest notification message may include, in a case that cells aremoved from a cell in which the MBS service can be received via the MTCHand/or the MRB to a cell in which the MBS service cannot be received viathe MTCH and/or the MRB but the same MBS service can be received via theDTCH and/or the DRB, information as to whether to receive the same MBSservice via the DTCH and/or the DRB. The MBS interest notificationmessage may include information as to whether to allow to receive theMBS via the DTCH and/or the DRB, and/or the MRB for receiving and/ortransmitting the MBS on a point-to-point basis, or information similarthereto, in the cell capable of receiving the MBS service via the MTCHand/or the MRB. The MBS interest notification message may be transmittedafter the SIB described in Step S1300 is received, in a case oftransition to the RRC CONNECTED state, or after transition to theRRC_CONNECTED state. The MBS interest notification message may betransmitted in a case that the SIB described in Step S1300 is receivedin handover, may be transmitted in a case that the SIB described in StepS1300 is received in re-establishment of the RRC connection, or may betransmitted in a case that the SIB described in Step S1300 is receivedin transition from the RRC_INACTIVE state to the RRC_CONNECTED state.

The processing unit 502 of the UE 122 may perform MRB release processingin order to stop reception of the MBMS session (Step S1308). Forexample, the MRB release processing may be started based on a case ofstopping the MBS session being received, a case of leaving from a cellin which the MRB is established, a case of leaving from a cell in whichthe MBS service can be received using the MRB, a case that the interestin the MBS service is lost, a case that reception of the MBS service isrestricted due to the restriction on the UE capability, and the like.The MRB release processing may be performed in a case that the UE 122 isin the RRC_IDLE state, may be performed in a case that the UE 122 is inthe RRC_INACTIVE state, or may be performed in a case that the UE 122 isin the RRC_CONNECTED state. In a case of performing the MRB releaseprocessing, the processing unit 502 of the UE 122 may perform a part orall of the following processing of (A) to (D). Note that the followingprocessing of (D) may be performed only in a case that the UE 122 is inthe RRC_CONNECTED state and/or the RRC INACTIVE state:

-   (A) release the PDCP entity of the MRB to be released;-   (B) release a physical layer configuration with the RLC entity of    the MRB to be released and the MAC related thereto;-   (C) notify a higher layer of information including a part or all of    a TMGI, a Session ID, a PDU session ID, and a QoS flow corresponding    to the released MRB and thereby notify the higher layer of release    of the MRB;-   (D) release an SDAP entity among the SDAP entities in a case that    the SDAP entity does not include an associated MRB and/or DRB.

Note that the MRB may be an MRB for receiving and/or transmitting theMBS on a point-to-multipoint basis, or an MRB for receiving and/ortransmitting the MBS on a point-to-point basis described above.

Note that, in step S1308 described above, the MRB release processing maybe started based on receiving or having received an RRC messageindicating releasing the MRB from the gNB 108. The MRB releaseprocessing may be started based on receiving or having received an RRCmessage including a part or all of session information of the MBSsession of interest via the DCCH logical channel from the gNB 108. TheMRB release processing may be started based on receiving or havingreceived an RRC message including a part or all of session informationof the MBS session of interest via the DCCH logical channel from the gNB108, and based on that the MRB corresponding to the part or all of thesession information of the MBS session of interest included in the RRCmessage is established. The MRB release processing may be started basedon initiating receiving the MBS on a point-to-point basis. The MRBrelease processing may be started based on receiving an MBS releaseindication from the higher layer, an indication of receiving the MBS ona point-to-point basis, or the like. The RRC message indicatingreleasing the MRB may include a part or all of the session informationof the MBS session. The part or all of the session information of theMBS session may be information including some or all of a TMGI, aSession ID, a PDU session ID, and a QoS flow corresponding to the MBS.The MRB release processing may be started based on receiving a controlinformation element that means stopping receiving the MBS session ofinterest from the gNB 108. The control information element that meansstopping receiving the MBS session of interest may include RNTIinformation and/or logical channel identifier used for receiving the MBSsession of interest.

Note that, in step S1308, MRB suspend processing may be performedinstead of the MRB release processing. The MRB suspend processing may beprocessing for suspending the MRB. For example, the MRB suspendprocessing may be started based on a case of stopping the MBS sessionbeing received, a case of leaving from a cell in which the MRB isestablished, a case of leaving from a cell in which the MBS service canbe received using the MRB, a case that the interest in the MBS serviceis lost, a case that reception of the MBS service is restricted due tothe restriction on the UE capability, and the like. In performing theMRB suspend processing, the RLC entity of the MRB to be suspended may bereestablished. In performing the MRB suspend processing, the downlinkreception may be stopped. In performing the MRB suspend processing, thePDCCH monitoring may be stopped. In performing the MRB suspendprocessing, information including a part or all of a TMGI, a Session ID,a PDU session ID, and a QoS flow corresponding to the suspended MRB maybe notified to the higher layer. Note that the MRB may be an MRB forreceiving and/or transmitting the MBS on a point-to-multipoint basis, oran MRB for receiving and/or transmitting the MBS on a point-to-pointbasis described above.

In step S1308 described above, the MRB suspend processing may be startedbased on receiving or having received an RRC message indicatingsuspending the MRB from the gNB 108. The MRB suspend processing may bestarted based on receiving or having received an RRC message including apart or all of session information of the MBS session of interest viathe DCCH logical channel from the gNB 108. The MRB suspend processingmay be started based on receiving or having received an RRC messageincluding a part or all of session information of the MBS session ofinterest via the DCCH logical channel from the gNB 108, and based on afact that the MRB corresponding to the part or all of the sessioninformation of the MBS session of interest included in the RRC messageis not suspended. The MRB suspend processing may be started based oninitiating receiving the MBS on a point-to-point basis. The MRB suspendprocessing may be started based on receiving an MBS suspend indicationfrom the higher layer, an indication of receiving the MBS on apoint-to-point basis, or the like. The RRC message indicating suspendingthe MRB may include a part or all of the session information of the MBSsession. The part or all of the session information of the MBS sessionmay be information including some or all of a TMGI, a Session ID, a PDUsession ID, and a QoS flow corresponding to the MBS. The MRB suspendprocessing may be started based on receiving a control informationelement that means stopping receiving the MBS session of interest fromthe gNB 108. The control information element that means stoppingreceiving the MBS session of interest may include RNTI informationand/or logical channel identifier used for receiving the MBS session ofinterest.

Note that, in an embodiment of the present invention, in a case that theUE 122 receives a message related to reconfiguration of RRC connectionand the DRB is established, in other words, in a case that the DRBidentity included in the message related to reconfiguration of RRCconnection is not present in the configuration of the UE 122, theprocessing unit 502 of the UE 122 may notify a higher layer that userplane resources for the PDU session have been established, based on acase that the SDAP entity for the PDU session corresponding to a fieldindicated by pdu-session included in the message related toreconfiguration of RRC connection is present and a fact that the DRBthat has been established or that is to be established is a first DRBfor the SDAP entity and/or the PDU session. Note that the above case“that the SDAP entity for the PDU session corresponding to a fieldindicated by pdu-session is present and a case that the DRB that hasbeen established or that is to be established is a first DRB for theSDAP entity and/or the PDU session” may be a case where the SDAP entityis the SDAP entity established in MRB establishment and the first DRBfor the SDAP entity and/or the PDU session is to be established or hasbeen established.

In an embodiment of the present invention, the UE 122 may receive amessage related to reconfiguration of RRC connection and performprocessing related to configuration of a radio bearer, and then based ona fact that an SDAP entity not including an associated DRB is presentamong the SDAP entities, the UE 122 may notify a higher layer that userplane resources for the SDAP entity not including an associated DRB havebeen released. In an embodiment of the present invention, the UE 122 mayreceive a message related to reconfiguration of RRC connection andperform processing related to configuration of a radio bearer, and thenbased on a fact that an SDAP entity not including an associated DRBand/or MRB is present among the SDAP entities, the UE 122 may releasethe SDAP entity not including an associated DRB and/or MRB.

In this manner, in an embodiment of the present invention, the UE 122can efficiently receive the MBS by using NR.

The radio bearer in the above description may be a DRB, may be an SRB,may be an MRB, may be a DRB and an SRB, may be a DRB and an MRB, may bean SRB and an MRB, or may be a DRB and an SRB and an MRB.

In the above description, expressions such as “linked”, “mapped”, and“associated” may be replaced with each other.

In the example of each processing or the example of the flow of eachprocessing in the above description, a part or all of the steps need notbe performed. In the example of each processing or the example of theflow of each processing in the above description, order of the steps maybe different. In the example of each processing or the example of theflow of each processing in the above description, a part or all of theprocessing in each step need not be performed. In the example of eachprocessing or the example of the flow of each processing in the abovedescription, order of processing in each step may be different. In theabove description, “to perform B based on satisfaction of A” may beinterpreted as “to perform B”. In other words, “to perform B” may beperformed independently of “satisfaction of A”.

Note that in the above description, “A may be interpreted as B” mayinclude the meaning that B is interpreted as A in addition tointerpretation of A as B. In a case that the above description contains“C may be D” and “C may be E,” this means inclusion of “D may be E.” Ina case that the above description contains “F may be G” and “G may beH,” this means inclusion of “F may be H.”

In the above description, in a case that a condition “A” and a condition“B” are conflicting conditions, the condition “B” may be expressed as“other” condition of the condition “A”.

Various aspects of the terminal apparatus according to embodiments ofthe present invention will be described below.

(1) An aspect of an embodiment of the present invention is a terminalapparatus for communicating with a base station apparatus, the terminalapparatus being configured to release, based on receiving, via a DCCHfrom the base station apparatus, an RRC message including a part ofsession information of an MBS session, an MBS radio bearer used toreceive the MBS session.

(2) An aspect of an embodiment of the present invention is a terminalapparatus for communicating with a base station apparatus, the terminalapparatus being configured to release, based on receiving an MBS sessionon a point-to-point basis, an MBS radio bearer used to receive the MBSsession.

(3) An aspect of an embodiment of the present invention is a basestation apparatus for communicating with a terminal apparatus, the basestation apparatus being configured to cause the terminal apparatus torelease, based on transmitting, via a DCCH to the terminal apparatus, anRRC message including a part of session information of an MBS session,an MBS radio bearer used to receive the MBS session.

(4) An aspect of an embodiment of the present invention is a method fora terminal apparatus for communicating with a base station apparatus,the method including releasing, based on receiving, via a DCCH from thebase station apparatus, an RRC message including a part of sessioninformation of an MBS session, an MBS radio bearer used to receive theMBS session.

(5) An aspect of an embodiment of the present invention is a method fora terminal apparatus for communicating with a base station apparatus,the method including releasing, based on receiving an MBS session on apoint-to-point basis, an MBS radio bearer used to receive the MBSsession.

(5) An aspect of an embodiment of the present invention is a method fora base station apparatus for communicating with a terminal apparatus,the method including causing the terminal apparatus to release, based ontransmitting, via a DCCH to the terminal apparatus, an RRC messageincluding a part of session information of an MBS session, an MBS radiobearer used to receive the MBS session.

A program running on an apparatus according to an aspect of the presentinvention may serve as a program that controls a Central Processing Unit(CPU) and the like to cause a computer to operate in such a manner as toimplement the functions of the above-described embodiments according tothe aspect of the present invention. Programs or the information handledby the programs are temporarily loaded into a volatile memory such as aRandom Access Memory (RAM) while being processed, or stored in anon-volatile memory such as a flash memory, or a Hard Disk Drive (HDD),and then read, modified, and written by the CPU, as necessary.

Note that the apparatuses in the above-described embodiments may bepartially enabled by a computer. In such a case, a program for realizingsuch control functions may be recorded on a computer-readable recordingmedium to cause a computer system to read the program recorded on therecording medium to perform the program. It is assumed that the“computer system” mentioned here refers to a computer system built intothe apparatuses, and the computer system includes an operating systemand hardware components such as a peripheral device. Furthermore, the“computer-readable recording medium” may be any of a semiconductorrecording medium, an optical recording medium, a magnetic recordingmedium, and the like.

Moreover, the “computer-readable recording medium” may include a mediumthat dynamically retains a program for a short period of time, such as acommunication line that is used to transmit the program over a networksuch as the Internet or over a communication line such as a telephoneline, and may also include a medium that retains a program for a fixedperiod of time, such as a volatile memory within the computer system forfunctioning as a server or a client in such a case. Furthermore, theabove-described program may be configured to realize some of thefunctions described above, and additionally may be configured to realizethe functions described above, in combination with a program alreadyrecorded in the computer system.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiments may be implementedor performed with an electric circuit, that is, typically an integratedcircuit or multiple integrated circuits. An electric circuit designed toperform the functions described in the present specification may includea general purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor, or theprocessor may be a processor of known type, a controller, amicro-controller, or a state machine instead. The general-purposeprocessor or the above-mentioned circuits may include a digital circuit,or may include an analog circuit. Furthermore, in a case that withadvances in semiconductor technology, a circuit integration technologyappears that replaces the present integrated circuits, it is alsopossible to use an integrated circuit based on the technology.

Note that the invention of the present application is not limited to theabove-described embodiments. Although apparatuses have been described asan example in the embodiment, the invention of the present applicationis not limited to these apparatuses, and is applicable to a stationarytype or a non-movable type electronic apparatus installed indoors oroutdoors such as a terminal apparatus or a communication apparatus, forexample, an AV device, a kitchen device, a cleaning or washing machine,an air-conditioning device, office equipment, a vending machine, andother household appliances.

Although, the embodiments of the present invention have been describedin detail above referring to the drawings, the specific configuration isnot limited to the embodiments and includes, for example, design changeswithin the scope that does not depart from the gist of the presentinvention. For an aspect of the present invention, various modificationsare possible within the scope of the claims, and embodiments that aremade by suitably combining technical means disclosed according to thedifferent embodiments are also included in the technical scope of thepresent invention. A configuration in which components, which aredescribed in the embodiment described above, having similar effects areinterchanged is also included in the present invention.

INDUSTRIAL APPLICABILITY

An aspect of the present invention can be utilized, for example, in acommunication system, communication equipment (for example, a cellularphone apparatus, a base station apparatus, a wireless LAN apparatus, ora sensor device), an integrated circuit (for example, a communicationchip), or a program.

REFERENCE SIGNS LIST

-   100 E-UTRA-   102 eNB-   104 EPC-   106 NR-   108 gNB-   110 5GC-   112, 114, 116, 118, 120, 124 Interface-   122 UE-   200, 300 PHY-   202, 302 MAC-   204, 304 RLC-   206, 306 PDCP-   208, 308 RRC-   310 SDAP-   210, 312 NAS-   500, 604 Receiver-   502, 602 Processing unit-   504, 600 Transmitter

1. A terminal apparatus for communicating with a base station apparatus,the terminal apparatus being configured to release, based on receiving,via a DCCH (Dedicated Control Channel) from the base station apparatus,an RRC (Radio Resource Control) message indicating releasing of an MRB(MBS (Multicast Broadcast Service) Radio Bearer), a PDCP (Packet DataConvergence Protocol) entity of the MRB.
 2. (canceled)
 3. A base stationapparatus for communicating with a terminal apparatus, the base stationapparatus being configured to cause, based on transmitting, via a DCCH(Dedicated Control Channel) to the terminal apparatus, an RRC (RadioResource Control) message indicating releasing of an MRB (MBS (MulticastBroadcast Service) Radio Bearer), the terminal apparatus to releasemessage a PDCP (Packet Data Convergence Protocol) entity of the MRB. 4.A method for a terminal apparatus for communicating with a base stationapparatus, the method comprising: releasing, based on receiving, via aDCCH (Dedicated Control Channel) from the base station apparatus, anRRC(Radio Resource Control) message indicating releasing of an MRB (MBS(Multicast Broadcast Service) Radio Bearer), a PDCP (Packet DataConvergence Protocol) entity of the MRB . 5-6. (canceled)